5 Causes of Engine ECU Failure (Why Does an ECM Go Bad?)

The ECU is the engine control unit of your vehicle. It is also often referred to as the PCM (powertrain control module) or ECM (engine control module).

This electronic module is a built-in computer which your vehicle depends on for managing a variety of its systems and functions. Think of it as the vehicle’s brain. The engine and drivetrain are the most dependent on the ECU.

Through a numerous array of electronic sensors, chips, and components within the vehicle, the ECU can transmit data feedback to the engine. The nature of this feedback will determine which function the engine will perform next.

This helps a great deal with calculating the proper amount of air and fuel needed for the internal combustion process. That way, better fuel efficiency can be achieved.

Common Reasons for ECU Problems

The ECU regulates virtually every important system and function in your vehicle. If you were to ever have a bad ECU, then many noticeable symptoms would present themselves. It wouldn’t take you long to realize the ECU was responsible.

However, what you may wonder about is why the ECU malfunctioned in the first place. There are lots of internal causes which could contribute toward this. Below are the top 5 causes of a bad ECU. Investigate them as soon as you notice problems with the ECU.

Read also: Car Immobilizer: Basic Function and Bad Symptoms

1) Dead Battery

old car battery

Car batteries have electronic cells which need to function in order for the ECU to function. If any of the cells in your car battery are dead, then your ECU is going to fail soon afterward. Once all the cells are dead, the battery is considered dead and your entire vehicle won’t be able to function.

You won’t be able to even start your vehicle and get the engine running. So, look out for the early warning signs of a malfunctioning ECU and then have your battery examined right away.

2) Corrosion

corrosion - water damage

The ECU has seals around it which are supposed to prevent moisture from entering inside. However, after a number of years, these seals tend to become worn out. If the seals become too worn, it will be easier for moisture to pass through them and enter the ECU.

Moisture is a bad thing to have in an ECU because corrosion will form on its components. If the corrosion is not cleaned away quickly, it will cause these components to get damaged. Then you will have a malfunctioning ECU.

Related: How to Clean Corroded Battery Terminals

3) Low Voltage

car wiring low voltage

The average ECU is expected to have at least 9 volts, but preferably 12 volts. There is wiring that runs into the harness of the ECU where you can check the voltage amount.

All you need to do is connect a voltmeter gauge to it. This device will be able to detect how much voltage is running through the ECU. If the voltage is 6 or less, then this is likely causing your ECU problems.

4) Bad Jump Starting

dead car battery

Whenever a jump start is performed on your battery, you need to ensure that the jumper cables are attached properly. If you attempt to jump start your vehicle with the cables attached incorrectly, then it could short out your ECU by causing it to spike too quickly.

This will require you to get the ECU repaired or possibly even replaced. This can end up costing thousands of dollars in expenses.

5) Bad Starter

bad starter motor

Many vehicles have starters with their own sensors in them. One of these sensors is the override sensor which manages how many volts the ECU will receive.

If this sensor were to go bad, then the ECU would not receive the correct amount of voltage. Then it would malfunction and cause further problems in your vehicle.

Another problem that could happen is if you replace your starter motor with a new starter that is not compatible with your vehicle’s ECU. Make sure any new starter that you purchase has the right sensors which can communicate with the ECU properly.

66 thoughts on “5 Causes of Engine ECU Failure (Why Does an ECM Go Bad?)”

  1. I have an intermittent ECU problem that seems to happen mainly in the morning when the headlamps are on , any ideas ?

    Reply
    • I’m sorry to hear the problem is intermittent. Those can be very tricky to diagnose.

      It’s hard to throw out too many ideas without more information. Providing your year/make/model and a description of the symptoms would help narrow down the cause tremendously.

      Before jumping straight to the ECU, I would start with the simple stuff: have your battery and alternator tested at a local parts store. Most places will do this for free.

      Reply
      • I change the cylenderhead gasket and oil seals due to leak but when i install all the parts and wirings and start the engine the engine only works in seconds and stop

    • My 2010 Toyota Corolla has a misfire in cylinder one.I have got new coils and my injectors are good.I have checked for a head gasket that is also good to.What could it be.The motor is a 1.8.

      Reply
  2. I have 07 Yukon with a 5.3 in it. I think the ecu is bad, the truck stalls with no spark, the check engine light is on, but it has no codes, I tried to reset the ecu all the different ways. The engine light won’t shut off.
    Can someone please give me some advice thanks

    Reply
    • See if the factory manual has a procedure for testing the ECU. You may find a manual for free by googling “07 Yukon factory manual”, but Haynes and Chilton manuals are inexpensive and do a pretty good job.

      Reply
  3. My battery keeps on draining. We changed the battery and alternator same problems exists. No grounded wires. I am thinking that it might be the ECU.

    Reply
    • I suppose it’s possible. However, I think it is more likely that there is a parasitic drain. This may come from the radio or an aftermarket security system, for instance.

      Reply
  4. I have intermittent issues with low idle RPMs and stalling while idling and while driving. Sometimes idle won’t go above 600 even while in park. Also AC/defroster is causing a drop in RPMs, even with a new IAC. When I reset the computer via battery disconnect, it idles perfectly for a while. Then hours or days later I’ll start it up and have it only at 600 RPMs again and wanting to stall when I put it into geae. Today it was idling for 15 minutes just fine, drove 15 minutes no problem, drove back 15 minutes, idled 15 minutes again, then finally it was stalling non stop. It started while I let my foot off the throttle as I approached a stop light. I was going 20-30mph. After that stall I couldn’t get it above 500 RPMs or so and it stalled about 5 times total. And that was only going a few blocks.

    2001 Mitsubishi Eclipse GS 4 cylinder 2.4L 215,000 miles

    Reply
    • BTW I did get 2 IAC codes. P0506 and P0507. But IAC wouldn’t cause it to stall while driving since IAC is only active while idle. I have 3 different IACs that I’ve cleaned and switched in with no change. So I dont think IAC is my problem unfortunately

      Reply
      • You may have an intermittent connection between the IAC and the ECU, a vacuum leak, or a dirty throttle body, IAC, or MAF.

        You can check for vacuum leaks using a smoke test. If you don’t have a smoke tester, you can build your own. Just google “diy smoke tester” and find one that works for you.

        If you have no vacuum leaks, I would try cleaning the parts above and see if it helps any.

        You may want to test your IAC just to confirm it’s not the problem. I found a good source for your car that may help: https://www.club3g.com/threads/how-to-testing-iac-idle-air-control.140906/

  5. Hi I was driving my when the temperature idle went to the limit & the warning was engine too hot. Called the AA & they said the thermostat sensor needed replacing. That was 6 months ago, today while getting my car washed the warning come on same reason as before so I changed the sensor again. Started the car & kept saying engine too hot, the engine was cold had plenty of water in it. Could the ECU mis diagnose, if so what causes this. I have a Peugeot 207cc 07plate

    Reply
    • It’s possible the ECU could misdiagnose, but it’s highly unlikely.

      Most thermostats are mechanical devices, not really sensors. They are basically valves held closed by a wax chamber. When the wax up it melts and expands, pushing the valve open. Once open, this brings cool water (or coolant) from the radiator into the engine and allows the hot coolant to move to the radiator, where it is cooled before reentering the engine block. Once the thermostat cools back down below its designated temperature, the wax solidifies and the valve closes again via a return spring.

      I would get a second opinion on that diagnosis. If an overheating issue is left unchecked, it can cause a more serious problem such as blown head gaskets (assuming that’s not the root cause).

      Reply
  6. My audi a3 2011/2012 refuse to start and I changed the battery but the battery run down again so I tried jumping the vehicle and connected the plugs wrong and it sparked. Still not getting any start but the lights on the dashboard is coming on saying drive to the nearest work shop
    What might be the problem or is the ecu damaged

    Reply
    • If you hooked up the jumper cables backwards it could be any number of things. I know a guy who did this and it fried the starter and popped the main 80 amp fuse. I’d take it to a shop to have it looked at.

      Reply
  7. 09 VW CC.
    Variety of problems, seemingly all random. Transmission dropped out of gear and won’t go back into gear. Input and output speed sensors are both inside the trans requiring pan removal so I’ve not gone in there yet. Engine runs great but, auto trans will not engage regardless of shifter position.
    And…cooling fans run at high speed from startup to 15 minutes after shut down even with cold engine and A/C off. Tested temp sensor and it works. Replaced FCU and fans behave the same. A/C will not turn on. Had it tested and the system overall is good but a command from the ECU is disallowing the compressor to engage.
    ECU acting up do you think?

    Reply
  8. Took my 2011 Dodge Grand Caravan to get inspection. Check engine light was on and reading fault codes in regards to the transmission. Garage recommended I take the van to the Dodge dealer. Dodge dealer tells me van needs a new transmission. I have them replace the transmission with a brand new one. They then call me and tell me that my starter was now making a loud noise so that would need to be replaced as well. The starter was fine with no problems when I dropped my van off to them. Over $5000 later I get my van back. Fast forward just 6 weeks. I’m driving my van when all of a sudden the battery light came on. I pulled over and turned off the van. It then would not start. Nothing would work not even the locks on the doors. Had the van towed. Garage now says I now need a new ECU, battery and alternator. Could the initial problem have been the ECU and not the transmission? My other question is could they have bypassed the surge protector on the ECU when they replaced the starter thus causing the ECU failure?

    Reply
    • It’s really hard to say without knowing the initial state of the van. It’s unlikely they bypassed the main fuse (probably the “surge protector” you’re thinking of).

      Reply
    • High fuel consumption and black smoke could be an indicator that the car is running rich. If it’s newer than 1995 you can scan for OBD2 codes to see if that tells you anything useful. You may see an issue with an O2 sensor or catalytic converter.

      If your vehicle uses OBD1 you can still scan for codes, but it’s done using a jumper wire between pins instead of a scan tool. Look up your owner’s manual (or a forum) for the proper procedure for checking codes on your vehicle.

      Reply
  9. Hi… I have a 2002 Chevy Avalanche, 1500, 5.3T motor. It idle is a little rough and has no power. The codes I get are P0170, P0174 and a p0300. Things I’ve replaced MAF, MAP, plugs, coils, wires, all 4 O2 sensors, the fuel pump, the intake manifold gaskets, all injectors. Smoke Tested also… found no leaks. Checked the back pressure of the one cat and it was good. Didn’t check the other cat though. After changing all these parts a lot of the misfires went away and it did run better. I’m still getting the same codes though. Though the power did get better it’s still has a hard time getting out of it’s own way. Going up hills is when it’ll start misfiring. My LT fuel trims are pegged at 25% and the short terms are hovering around 0 at idle. When I start giving it the gas the short terms go up and the long terms go down but the average together is around 25%. I have a tech 2 scanner I’m using. Why I think it maybe the ECU is because I keep loosing signal on my Tech 2. I bought the Tech 2 used so I hope it isn’t that. So, I had a constant reoccurring of #6 misfiring for the longest time. Even after I switched coil, plug and wire it would still misfire. Checked for actual spark… and that was good. Then all of a sudden the #6 misfire went away as 2 other misfires appeared. swapped components and checked it again and now the misfires were on two other unrelated cylinders. I am totally at a loss… please help, thanks

    Reply
    • That’s very strange. It sounds like you have your bases covered with the simple tests; you certainly covered all my initial suggestions.

      The fact that your short term fuel trims are around 0 at idle is a good sign. I am more concerned with the short term fuel trims rising as you increase engine speed. This leads me to believe there is a fueling issue where the engine is not getting enough fuel under load.

      Since you already smoke tested and verified you have no leaks, I would take a closer look at the fuel system. Perform a fuel pressure test to make sure you’re getting adequate pressure at the fuel rails, particularly on bank 1 where the code was thrown. If one rail is bad or leaking, I would expect a higher ST fuel trim on that bank.

      You might consider pulling the injectors and either have them cleaned or tested to make sure they aren’t clogged, but since the misfires were across multiple cylinders I am more inclined to believe it is an issue with the fuel pressure regulator or fuel rail on bank 1. Good luck, hope that helps a bit.

      Reply
      • Hi Sean.. thanks for the reply. Here’s what I have done within 8 months ago… I was told that the fuel pressure for the T model Avalanche is to be 55psi or higher. After changing the fuel pump 3 times before getting one to operate at somewhat of that 55psi range. Maybe this is the problem??? The last fuel pump puts out 50psi at idle and pegs out at 59psi at WOT. I figured is was good. Then I changed some fuel lines, fuel filter and the injectors. These injectors were to be like a factory upgrade injector without having to retune the motor. The original injectors were, I think, 48-50psi to open and they were also a 2 hole injectors. These upgrades were 28psi to open and was a 4 hole injector. Could either of these be the problem? Could it be the ECU?

      • Sorry just thought of something else too… I did replace the fuel regulator and it seems to be working… but when I was doing the smoke test a little smoke was weeping out the very top of the regulator. Is that normal?

      • Check the flow rate on the injectors to make sure they are similar to the factory ones. Do you still have a set of factory injectors? I would try them to see if it fixes the problem. I am skeptical of changing injectors like that without retuning… that may be your issue.

        I don’t think the fuel pressure regulator should let smoke out like that.

      • Hi Sean… I’ve been looking around the internet and came across the fuel pressure specs. I found this “4.8L, 5.3L, 6.0L or 8.1L your fuel pressure should be 55 – 62 psi with the key on – engine off”. The fuel pump I have now has the pressure of 50-59 psi. In your professional opinion is this sufficient enough? Plus also, I’m going to order a original set of 2 hole injectors for the truck to see if makes a difference as you said.

      • I’m not sure about the fuel pressure. I would do a bit of searching on the forums to see if you can compare your numbers to those of other owners with the same engine.

        I don’t like to change a bunch of parts at the same time because it often makes it really hard to troubleshoot when something goes wrong. Is a new part defective, incompatible, or hooked up wrong? Which new part is causing the issue? Did I simply break something while I was in there? Am I experiencing symptoms from two separate issues?

        If you still have your original fuel pump, you could try switching back and checking the pressure to see if it’s similar.

      • Hey Sean, just an update… found remanufactured injectors and ECU at an affordable price. You were right in steering away from the ECU. Replaced the ECU… same problem still exists. Just waiting in the injectors to come in.

      • Hi Sean… the new fuel injectors worked for the fuel trims. As far as fuel trims go it’s running perfect. But, now I have what seems to be a constant misfire on #2 and 6. Thanks

  10. I have a 2019 Hyundai Kona with less than 10k mileage. One day both stability control and downhill brake control lights turned on and won’t go off. The following day the check engine light turned on. All three lights won’t go off and I started to feel the engine having a hard time moving from standstill every time the vehicle senses the car is in a sloping position. Service told me the ECU will need to be replaced. I asked him what was the possible cause of the early ECU malfunction but he said he didn’t know as well. Do you have an idea? Thanks.

    Reply
  11. I have a jeep liberty ‘05. It keeps blowing asd fuse. Gauges and warning lights keep coming on. Won’t crank. Any idea where to start? Are these ECU symptoms?

    Reply
  12. Hi I have a Citroen c4 hatchback 2010
    I have an intermittent problem .
    My car can start perfectly fine one day and the next not start at all completely dead no radio no lights nothing which can last a few days and out the blue starts again.
    I called the RAC out they have told me I have a ECU problem
    And the car has had it .
    Any advice would be appreciated .

    Reply
    • Before you try to replace the ECU, check your battery connections. Make sure the terminals are tight and free of corrosion. I’ve had a car that wouldn’t start because the corrosion was so bad.

      Reply
      • Sorry for the late reply
        I had a diagnostic test done by the RAC .
        can a bad battery connection show as a ECU problem on a diagnostic test just wondering as the RAC told me to get rid of my car
        Thanks for your help .

  13. Thank you I will do that.
    Can you tell me if the RAC done a diagnostic on my car and it came up with ECU problem
    Can a battery cause that to come up as a ECU.
    Thank you for your help .

    Reply
  14. My car a missing problem which is unstable slow speed . It comes down automatically and its also raise . There is also staring trouble like engine is not stable while i jumb small humbs and gutters . Totally body is shivering while my car showing missing .

    Reply
  15. Hi everybody.
    Got a mercedes cla amg 45 and took it for polish shampoo. Drove the car there all okay. I got a call from the shop that the car wasn’t starting on the next day. They started it, moved it to the first washing step and then they said it didn’t start. They tried to jump start it (don’t know if smth stupid happened there, incorrect connections) and when I went there I air-sprayed at ECM cables and drops of water came out. They denied they washed the engine and the owner later said he did it himself with vapor. The thing is I took it to mercedes repair shop they opened the ECM and said they found corrosion in it and that it’s hard to define the actual reason for the failure. IF that was the case, wouldn’t I had some indication from the slow corrosion process that things are not right i.e. lights, applications, sensors…?

    Reply
  16. My 2015 Nissan Altima was having issues. We ran codes and changed all the sensors that were identified. Then one day it just stopped. We had it checked and now we are getting a code related to voltage and the ecm. The car will only run for 8-10 seconds at a time. How expensive will it be to repair?

    Reply
    • Those codes just give you insight into the root cause; the sensors they reference may not be the root cause of the issue themselves.

      In some cases, an electrical issue could cause several systems to fail due to incorrect voltage, too much resistance, etc. Changing each sensor isn’t going to help in this situation, since the problem is with the wiring somewhere. I’ve seen an ignition switch failure that triggered the airbag light, ABS light, check engine light, and stopped the power windows from working.

      More diagnostic testing is needed before you can get an accurate repair estimate.

      Reply
  17. Hi
    My Toyota corolla automatic developed a problem where the accelerator is not changing. It drives slowly with the gears not selecting. I change the TPS but still, could it be the ECM?

    Reply
  18. my Cadillac escalade made aloud pop under the hood from the left hand side. my truck then cut off as i pulled over.i thought i had a blow out but my tires was good..when i tried to start it it would not start. i changed fuel pump,spark plugs,battery starter still will not start. it turns over though. i see the pcm is under the hood under the left side could this be the cause?

    Reply
    • I’m not sure. If you heard a loud pop, something should be obviously broken or out of place. I’d poke around a bit more, then check for the presence of fuel and spark when you crank it.

      Reply
  19. My ecu went wrong because moisture got in, I’ve replaced it, the ecu board itself has a metal cage and in my car this goes inside a plastic box on the engine bay, I don’t how how water got in inside this plastic box, I’m thinking of sealing the box, so this new ECU don’t go wrong, what kind of RTV silicone or substance would you recommend to seal this box?

    Reply
  20. 08 sub outback 141k miles

    14 months ago I was getting a check engine light and found the error code p0306, cylinder 6 misfire. after changing the spark plugs and ignition coil packs I was still getting the failure. a subaru specialist diagnosed a bad ecu and changed it.

    last week I got another check engine light with p0301 & p0306, cylinder 1 & 6 misfire. the subaru dealership diagnosed another bad ecu. from what you’ve listed here I’m guessing that the voltage is too much or too little and shorting out the ecu. i know little about the electronics, how would I be able to diagnose what the cause could be as far as an improper voltage? are there other common causes to ecu failure??

    Reply
    • How did the dealership identify the ECU as the root cause? Since the misfire keeps returning I’m wondering if the issue lies elsewhere. If I were in your situation, I would start my troubleshooting at the very basics, assuming I had no info about the problem at all.

      When doing diagnostic work, take care to not assume a component is good until you have tested and verified that the component is working properly. This is the only way to reliably narrow down the problem scope and find the root cause.

      Check for technical service bulletins (TSBs) on your car related to misfire codes. The Subaru community is a very active and helpful one. Browse the Outback forums for people who had the same issue. You can try googling something like “08 outback H6 cylinder 1 and 6 misfire”

      To rule out air and fuel, check fuel trims to make sure it isn’t running too rich or lean, as this could also cause a misfire. Fuel trims can be checked with a scan tool. Strong compensation one way or the other could mean a vacuum leak, clogged or leaky injector, etc.

      If you have an electrical short, a fuse should blow to prevent damage to the ECU. Check all fuses to make sure none are blown. For any further electrical troubleshooting, you’re going to need a multimeter and a wiring diagram for your vehicle handy. Do note that fuses probably won’t protect the ECU if there is a bad connection on the ECU’s circuit board that is causing some short or open circuit.

      It never hurts to test the health of your battery and alternator before diving into an electrical issue either. Good luck.

      Reply
  21. I have a 2009 Saturn Vue with 132,000. It runs great so long as the codes don’t go off. The Service Stabilitrak code recently started going off, then the brake code and the ABS code, then all of a sudden that little car with the wrench inside came on and the car drove in safe mode. I had it towed, and looked at and the mechanic said there are 14 codes in the ECM alone which suggests communication issues. He also said there is a possible internal fault in the PCM. I thought the ECM and PCM were the same – are they 2 separate modules in a Saturn? Well, I agreed to have them test it further because these codes only go off intermittantly then stop for a couple days, then start going off again. What do you think?

    Reply
  22. How was the ECU identified as the root cause? Since the misfire keeps returning I am wondering if the issue lies elsewhere, such as a bad ground or ignition coil.

    Reply
  23. Wondering if maybe you could explain why when I test a specific sensor on my ECM(ECU) for my 2010 Subaru Forester I am not getting the same results as the dealerships Special Scan Monitor.

    There monitor say everything is within range, but when I do the multimeter test from the manual I’m not getting the same values actually way out of range. I am on the correct pins and following the instructions to the “t”. also every time I do this it triggers a bunch of engine codes, which forces me to unplug the battery to reset everything then they never come back….

    Any thoughts?

    Reply
  24. I have a DS5 and it has cut out on me with only an inadequate 1 second warning of engine failure on 2 occasions over the past 2 year. Last time it was the main fusebox that needed replacing but this time it looks like the ECU will need replacing and Citroen have quoted £8000 to get it fixed if they don’t find another cause. I don’t think the 2012 DS5 Hybrid is worth that much and what I worry about is that the hybrid batteries might also need replacing and this could all end up devastatingly costly. A car that shuts down after a 1 second warning, to me, is extremely dangerous especially when driving in the fast lane on a motorway and it beggars belief that a big company like Citroen do not put a failsafe in place? I don’t really know what I should do; Cut my losses and run or go the whole pricey hog and get it fixed, if that is actually possible. I don’t know if Citroen would give me any compensation and wouldn’t know where to begin to ask? It’s a huge worry!

    Reply
  25. I’m chasing a PO172 code on my 01 Tacoma 2.7 after addressing a misfire on #3 cylinder. Changed plugs and injectors and ran okay for a couple weeks then PO172 code comes up. Changed O2 sensors, MAF, fuel pressure regulator, ERG, and ECT. Mechanic told he has no idea why fuel trims off and that I should change the ECM. Took it to another mechanic who looked at it and told me he has no idea what’s wrong with it but doesn’t think its the ECM. So anyhow, I”m going to replace the ECM. If that doesn’t work do you think its possible that I did something wrong when installing the injectors? I’m not getting and fuel leaks and they are Denso, however I didn’t replace the seals.

    Reply
    • I agree with your second mechanic; I have no idea why fuel trims are off but don’t think it’s the ECM. Are the fuel trims off only on cylinder #3?

      Try switching the spark plugs and injectors around and see if the problem follows them around. Don’t switch the injectors and plugs at the same time though – switch the injectors, see if the problem follows the old #3 injector around, then repeat the process with the spark plugs.

      Might not hurt to test the voltage received by each injector either.

      Reply
  26. My 2000 VW Beetle 1.8 turbo mst have an intermittent parasitic batttery drain, perhaps due to the turbo warmdown ciruitry. I am having difficulty diagnosing it (my multiemeters just read zero milliamps I will keep trying) and until I figure that out, if ever, I was thinking of disconnecting the battery when I park overnight. I am worried that the ECU might lose important settings to the point the car won’t start or run decently or that I will have to keep dealing with a throttle reset and other headaches. On the other hand, every time I had a dead battery, such as when the car was down for several weeks, all i had to do is jump start the car and it ran fine. Any thoughts?

    Reply
    • Most ECUs have some form of non-volatile storage to save critical information, even when there’s no power to the ECU. Disconnecting the battery should work fine in the short term until you’re able to diagnose the parasitic drain.

      Reply
  27. My car has been experiencing overheating problems for about a month. I have a 2011 Nissan Pathfinder with about 130K miles. We replaced the thermostat (double checked it – its good and opens at 180 degrees), replaced the radiator cap, replaced the radiator, flushed the radiator, and burped her several times. I hooked up my code reader last night and she finally showed codes P1217 & P0113. I looked them up and I’m wondering if it is my Mass Air Flow sensor, because my Intake Air Temperature sensor is built into the MAF. We checked our fan clutch and compared it to a brand new one and it’s fine too, we also tested my water pump and that’s working just fine as well. I have no leaks (other than when I overheat – water is pushed back out of the reservoir), but if I have my heater on it works as a second radiator and prevents my car from entering the ‘hot zone’. Could my MAF cause the overheating issue?

    Reply
    • No, the MAF probably isn’t causing the overheating issue. You might want to do a leak down test. While performing the test, if air leaks into the cooling system you probably have a failed head gasket.

      Reply

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