6 Symptoms of a Bad Camshaft Position Sensor (And Replacement Cost)

Most drivers don’t think about their camshaft position sensor until something goes wrong. This small yet important sensor helps control your engine’s timing, and when it fails, it can make your car behave in strange and unpredictable ways.

Let’s look at the most common symptoms of camshaft position sensor failure, how to correctly diagnose it, and how much it’s going to cost to fix.

What is a Camshaft Position Sensor?

The camshaft position sensor is an electronic device that monitors the rotation and position of your engine’s camshaft. This information helps your engine’s computer (ECM) control the timing of fuel injection and spark plug firing.

Think of this sensor as a timing coordinator. As your engine runs, the camshaft rotates to open and close the valves that let air and fuel into the cylinders. The sensor tracks this movement and sends signals to the ECM, allowing it to sync fuel injection and ignition timing with the exact position of the valves.

Most vehicles have one or two camshaft position sensors, depending on the engine design. Normally, they’ll be mounted on the cylinder head or timing cover, close to the camshaft they monitor. Some engines, especially those with variable valve timing, may have additional sensors.

Signs of a Bad Camshaft Position Sensor

1) Check Engine Light

One of the very first symptoms of a failing camshaft position sensor is usually an illuminated check engine light. Modern vehicles monitor sensor signals constantly, and when the ECM detects irregular readings from the camshaft sensor, it triggers the check engine light.

The most common error codes related to the camshaft position sensor are P0340 and P0341. These codes specifically indicate a problem with the sensor’s circuit or signal. However, you might also see codes like P0016 or P0017, which suggest the camshaft timing isn’t matching what the computer expects.

2) Engine Starting Problems

Since the sensor helps the ECM determine the position of the valves, a faulty sensor can confuse the timing of fuel injection during startup.

Your engine may crank longer than usual before starting, or in some cases, it may not start at all. This happens because without accurate camshaft position data, the ECM can’t properly time the fuel injection and spark, making it harder for the engine to fire up.

3) Poor Engine Performance

Sometimes, your engine’s performance will take a noticeable hit with a faulty sensor. Again, since the ECM relies on the sensor’s data to control fuel injection and spark timing, incorrect signals can cause the engine to misfire or run rough.

You might experience random stumbling, hesitation when accelerating, or rough idling. In a few cases, the engine may even stall unexpectedly while driving or at stop lights. This all happens because the ECM is making incorrect adjustments based on faulty information from the sensor.

4) Jerking or Surging While Driving

Sometimes a failing camshaft position sensor will cause your car to jerk or surge while driving at constant speeds. It’ll feel like someone is repeatedly pressing and releasing the gas pedal, even though your foot position hasn’t changed.

Once again, this is due to incorrect sensor readings which cause the ECM to constantly adjust the fuel and timing. These constant adjustments result in uneven power delivery to your wheels, creating that jerking or surging sensation.

5) High Fuel Consumption

A failing camshaft sensor often leads to worse fuel economy. When the sensor sends incorrect data, the ECM might inject too much fuel into the cylinders or time the injection poorly. Either way, more fuel than necessary will be used so you’d literally be burning money.

This increased fuel consumption often goes hand in hand with poor performance. If you start noticing that you’re having to fill up more often and your engine isn’t running quite right, a bad camshaft position sensor could be the cause (among other things).

6) Limp Mode Activation

In rare cases, a malfunctioning camshaft position sensor can trigger limp mode (a safety feature that limits engine power to prevent damage). If your car suddenly loses power and won’t rev past a certain RPM or speed, the ECM may have entered limp mode due to receiving bad signals from the sensor.

Limp mode usually allows you to drive slowly (limp home) to a safe location or repair shop, but with a significant reduction in power. Some vehicles will also disable features like cruise control when in limp mode.

Camshaft Position Sensor Replacement Cost

While the symptoms can be severe, camshaft position sensor replacement is relatively affordable (in most cases) compared to many other engine-related repairs.

A new camshaft position sensor typically costs between $20 to $200, depending on your vehicle make and model and whether it’s an aftermarket or OEM sensor. But keep in mind that your particular engine may have two or three of these sensors, so it can add up.

In many vehicles, access to the sensor(s) is fairly simple making this an excellent DIY job. It might only take you 15-30 minutes.

You can find replacement camshaft position sensors at most auto parts stores like AutoZone, O’Reilly Auto Parts, or NAPA. Online retailers like RockAuto or Amazon often have the best prices, but make sure you double-check the part number and vehicle fitment before ordering.

If you choose to have a professional mechanic do the work, expect to pay for about 1-2 hours of labor. Labor rates vary by location and shop, but typically range from $80 to $140 per hour with dealerships being near the top end of that range.

If your vehicle is still under warranty, you’ll definitely want to visit your dealership. They can verify if the repair might be covered under warranty and will use genuine OEM parts for the replacement.

Diagnosing a Bad Camshaft Position Sensor

Before you spend money replacing your camshaft position sensor, it’s important to confirm that it’s actually the source of your problems. Several other issues can cause similar symptoms, so proper diagnosis is quite important.

Using an OBD2 Scanner

The easiest way to start diagnosis is with an OBD2 scanner. If your check engine light is on, the scanner will read any stored error codes. Common camshaft position sensor codes include:

• P0340: Camshaft Position Sensor Circuit Malfunction
• P0341: Camshaft Position Sensor Performance
• P0016/P0017: Crankshaft/Camshaft Timing Correlation Error

Visual Inspection

Take a look at the sensor and its wiring. You’re checking for:

• Damaged, loose, or corroded wiring connections
• Oil leaks around the sensor (which can damage it)
• Physical damage to the sensor
• Loose mounting bolts

Testing the Sensor

A multimeter can help verify if your sensor is bad. With the key on but engine off, you should see proper voltage at the sensor connector (usually 5 or 12 volts, depending on your vehicle). A repair manual for your specific vehicle will list the correct voltage specifications and testing procedures.

Common Misdiagnosis

Sometimes problems that seem like a bad camshaft sensor can actually be caused by:

• Failed crankshaft position sensor
• Timing belt/chain issues
• Wiring problems
• Low engine compression
• Vacuum leaks

What Causes the Sensor to Fail?

• Age and Wear: Over time, the internal components naturally degrade from constant heat cycles and engine vibration. Most sensors last between 100,000 and 150,000 miles. But it’s possible for it to fail much sooner or even last the life of the vehicle.
• Oil Contamination: Leaking valve cover gaskets or camshaft seals can allow oil to seep into the sensor’s electrical connections and internal components. Once oil gets inside, sensor failure is inevitable.
• Excessive Heat: While designed to handle high temperatures, prolonged exposure to higher-than-normal engine heat can damage the sensor. This is especially common in engines that run hot or have cooling system issues.
• Electrical Problems: Short circuits and voltage spikes can burn out the sensor’s internal components. Bad grounds, damaged wiring, or other electrical system issues often lead to premature sensor failure.
• Physical Damage: The sensor can be damaged during other repair work or from road debris (although damage while driving is extremely rare).

Can You Drive With a Failed Camshaft Position Sensor?

While it’s technically possible to drive with a failing camshaft position sensor, it’s not a good idea. The most immediate concern is safety. Uexpected stalling or power loss while driving could leave you stranded in a dangerous situation, especially on highways or busy intersections.

Running your engine with incorrect timing can also cause serious damage. Your car’s computer needs accurate camshaft position data to properly control fuel injection and spark timing. Without this information, your engine could be running in ways that cause premature wear or serious mechanical problems.

Even if the car seems to run okay, you’re likely wasting fuel due to improper timing. The bad sensor can also cause your engine to run rich or lean, which could cause you to fail emissions testing (although a check engine light will do the same).

Perhaps most concerning is the unpredictable nature of sensor failure. Your car might run fine one moment and have serious problems the next. This unpredictability makes it risky to rely on the vehicle for important trips.

If you suspect your camshaft position sensor is failing, it’s best to have it diagnosed and replaced as soon as possible. It’s just not worth the stress of having to worry about potential engine damage or getting stranded.

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Kevin

Kevin has been fascinated by anything automotive since his first go-kart as a kid to his time working as an auto tech for Dodge after obtaining his degree in automotive technology. When he's not working on cars or writing about them, you can find him and his E36 M3 at an event with the local chapter of the BMW CCA.

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