9 Symptoms of a Failing Camshaft Sensor You Shouldn’t Ignore

9 Bad Camshaft Sensor Symptoms to Watch Out for

Reduced engine power, starting problems, increased emissions — camshaft sensor symptoms can show in many ways. They mainly indicate a problem with the part, which, if not operational, causes the ECM to lose proper control of engine systems. Here’s more about these signs.

Bad Camshaft Sensor Symptoms

The ECM (Engine Control Module) relies on various sensors to control engine operation. One of them is the camshaft sensor, abbreviated as CMP. This part provides the ECM with cam position and speed, enabling it to regulate combustion. As such, its failure can affect the car’s performance in many ways, exhibiting cam sensor symptoms. They include:

1. Check Engine Light

The ECM constantly checks the sensor’s health. Upon detecting a problem, it turns on a check engine light. But while that is possible, it’s good to note several other issues that can cause the engine light. Confirm if the CMP is to blame.

2. Engine Failing to Start

The car fails to start, even with the starting system working correctly. The problem happens when the CMP cannot feed the ECM with camshaft position information, resulting in fuel injection and sparking issues.

3. Vehicle Stalling

In the worst of situations, your car may stall. Stalling indicates the fuel injectors are not delivering fuel as they should, with the possibility of the sensor being the cause. This problem can be dangerous, and a proper diagnosis is required.

4. Rough Idling and Misfire

The engine has a rough idle, showing a disrupted combustion process. In addition, a cylinder may occasionally fail to fire, indicating an ignition timing problem. The ECM could have issued the wrong commands due to a failing camshaft position sensor or other causes.

5. Reduced Engine Performance

The engine power reduces, and you have difficulty accelerating. It’s one of the most probable camshaft position sensor symptoms you should not overlook. In addition to causing a drop in your engine’s performance, it could cause it to get damaged.

6. Poor Fuel Economy

The engine becomes inefficient, and your car consumes more fuel than usual. The fuel economy problem results from data inaccuracies caused by the CMP. It shows the ECU is providing incorrect instructions to time various processes, including gas intake and ignition.

7. Shifting Problems

A bad cam-sensing device affects the transmission. The engine control module does not receive correct cam speed and position data, which affects its ability to control ignition and combustion. That, in turn, causes shifting problems. Your car may also go into limp mode to prevent further damage.

8. Smell of Fuel

There is the smell of unburned fuel. This symptom shows an incomplete combustion process, leading to some fuel mixture reaching the existing pipe. But while this is one of the cam sensor fault symptoms to look out for, it’s good to note that other things can cause it.

9. Failed Emissions Test

With the fuel injection and ignition systems not working correctly, the engine becomes less efficient, increasing the amount of emissions. As a result, failing the emission test is one of the most common symptoms to look out for.

Check engine light due to a failed CMP sensor
Check engine light due to a failed CMP sensor
Resource: https://www.chryslerminivan.net

What Happens When a Camshaft Sensor Goes Bad?

A failing CMP sensor cannot send correct cam data to the ECM. As a result, the engine suffers. The combustion process becomes inefficient, leading to problems like reduced power, misfire, and increased emissions.

Several things can cause the CMP to fail. Given its location, it gets subjected to harsh conditions like heat, vibrations, and sometimes metallic debris. That can take a toll on it, causing it to fail over time.

The CPS also fails if its electrical connections are faulty due to corrosion or breakage. Regardless of the cause of failure, you must quickly act if you notice any symptoms.

With no proper engine control, your car could become dangerous to drive. Its failure also causes issues that could quickly damage engine components. In some vehicles, failure may cause the car to enter “limp mode” and prevent further damage.

Cam sensor position in an engine
Cam sensor position in an engine
Resource: https://www.cruzetalk.com

How to Replace Camshaft Sensor

The CPS is not repairable; you can only replace it with a new one. It’s also a relatively inexpensive part and won’t cost much compared to the problems it causes. Here is how to replace one.

Materials and Tools:

  • Wrench or socket set

  • Screwdriver

  • Code reader or diagnostic scanner.


  • Step 1: Park safely on flat ground, turn the car off, and use the parking brake. Disconnect the battery’s negative terminal.
  • Step 2: Determine the part’s location. It’s mounted in the cylinder head on most cars, close to the camshaft. Refer to your car’s manual if unsure.
  • Step 3: Remove any components that may be obstructing your access to it, such as wires or the air intake parts
  • Step 3: Unplug the wiring connector or harness. Now, remove the faulty CMP. One or two bolts or screws typically hold it.


  • Step 4. Place the new CMP on the mounting surface. Ensure its proper alignment. Secure it with the fasteners you had earlier removed. Use the correct torque to avoid causing damage.
  • Step 5: Re-attach the connector and reconnect the battery. Start the car to see if it cranks and runs smoothly. The earlier camshaft sensor symptoms should not return. If they do, the problem is elsewhere.
  • Step 6: Clear the old fault codes using the scanner or code reader. You may also want to check if there are any other codes. Ensure all electrical connections are in good condition and working: no breakage, dirt, corrosion, or looseness.
Bad CMP sensor
Bad CMP sensor

Is it Safe to Drive with a Bad Camshaft Position Sensor?

Based on the discussed camshaft sensor symptoms, you may suspect yours to be failing and wondering if you can still use the vehicle. So, can you drive with a bad CMP? If so, for how long?

We do not recommend operating your car if the ECU cannot sense the position of the cam and its speed. In addition to risking engine damage, your vehicle could stall due to a disruption of the combustion process.

The best advice is to change the part as soon as you can. CMP replacement should cost you between $100 and $150 in labor charges. The part itself goes for less than $50


A failing CMP can cause your engine to malfunction or even get damaged. Your car loses power, misfires, and may even stall while driving. The symptoms explained in this article should help you tell when it starts to fail.

WanTuo is your most trusted manufacturer and supplier of camshaft position sensors. Our sensors are built to last, even in harsh conditions.


I'm Louis, a seasoned writer specializing in auto parts, particularly the science behind components like cylinder heads and pistons. With over a decade of experience and a background in mechanical engineering, my articles reflect a commitment to professionalism, blending technical insight with engaging content.

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