(Updated on December 31, 2021)
The engine control module (ECM), also referred to as the engine control unit (ECU), is a critical component which links your engine to the central computer of your vehicle. The ECM manages most of the functions of the engine, based on the information it receives from other systems and electronic components within the vehicle.
If the ECM were to become damaged or faulty, then it could spell trouble for the entire engine because it would not be managed properly. If the engine is not managed properly, then it is not going to operate properly and then your car won’t work properly. You see how it all links together?
Top 5 Symptoms of a Bad Engine Control Module
If you have a bad ECM in your vehicle, the symptoms will become more than obvious. But it is important that you recognize these symptoms as they arise, so you can do something about it right away.
Here are 5 common symptoms of a bad engine control unit in a vehicle.
1) Bad Engine Performance
A big symptom that you will notice from a bad engine control module is poor engine performance. Your engine will start to have bad timing and it won’t get power as efficiently as it used to from the internal combustion process.
This will ultimately affect your ability to accelerate the vehicle as you step on the gas pedal. If you notice any kind of acceleration issues, then it could be because of a bad engine control module.
2) Engine Stalling
Along with a weak engine performance, you could actually experience the engine misfiring or at least stalling a lot. This doesn’t necessarily mean anything is wrong with the engine itself, but it does mean there could be a malfunction taking place with the engine control unit.
The engine stalling will likely be inconsistent, so it may stall sometimes and then clear up at other times. But even if you experience it one time, you should do something about it right away.
3) Bad Fuel Economy
When the engine control module is glitchy, the engine might not always know the right amount of fuel to deliver to the internal combustion process. Often times, it will start burning more fuel than usual just to sustain its normal driving needs.
This will drive down the vehicle’s fuel economy, which means you’ll be paying more money at the gas pump.
4) Check Engine Light
One of the most obvious indicators of a possible ECM issue is when the check engine light illuminates on your dashboard. This warning light could mean any number of possible issues with the engine.
If you’re lucky, it will only mean the engine control unit is in trouble and not the entire engine itself. You will need to use a diagnostic scanner to confirm what the actual issue is.
5) Car Won’t Start
If your car simply does not start and you can’t figure out why, then it may be because the engine control module has gone bad or stopped functioning completely.
You may still get your engine to crank but that’s all it will do. If the engine control unit is not working, then it won’t be able to send electronic input to the engine.
Average ECM Replacement Cost
If you know for sure that your engine control module is not working properly, then you will need to replace it if you want to keep your car driveable.
The replacement cost of the engine control module is definitely not cheap and starts at $450, but could go up as high as $1,750. The exact cost will mainly depend on the make and model of your vehicle. Used or refurbished ECUs can often be had at a huge savings.
The parts expense will cost the most as they’re usually priced somewhere in the range of $350 to $1,550. The labor costs will likely be somewhere between $100 and $200.
So, even if you find an inexpensive (qualified) mechanic to perform the replacement job, you will still need to spend a great deal of money on the engine control module itself.