If you’re experiencing issues with your car, one of the first things to check is the camshaft position sensor. This component sends signals to the engine control unit and if it’s malfunctioning, it could lead to a variety of issues.
In this blog post, we’ll look at the signs of a malfunctioning camshaft position sensor and what you should do if you suspect yours to be the problem.
Signs of a malfunctioning camshaft position sensor include an illuminated check engine light with P0340-P0349 trouble code, delays starting the car more slowly than usual, poor fuel economy, rough idle, lack of acceleration as before, failed emission test results, difficulty shifting gears, a smell of unburnt gas, engine stalling or no start at all.
Key Takeaway
Symptoms of a Bad Camshaft Position Sensor: What to Look Out For
- Check engine light will ignite
- Car takes longer to start than usual
- Bad fuel economy
- Rough idle
- Car not accelerating as before
- Failed emissions test
- Difficulties in shifting gears
- Your car may be smelling of unburnt fuel
- Engine stalling
- No start at all
What Is The Purpose Of Camshaft Position Sensor
The Camshaft Position Sensor is responsible for monitoring the position and rotation speed of a camshaft. It relays this data to the engine control unit, which uses it to adjust ignition timing and fuel injection system components. Consequently, your engine runs smoothly and efficiently.
Camshaft position sensors in cars come in two varieties, inductive and Hall effect sensors. The former utilizes an electromagnetic field to generate a signal while the latter utilizes magnetism. Both types of sensors are employed to precisely measure the position of a camshaft.
The inductive sensor is the most popular type of camshaft position sensor. These devices are found on nearly all modern vehicles and work by using electromagnetic fields to generate a signal that then gets sent to an engine control unit (ECU). The ECU uses this information to calculate the position of the camshaft.
Hall effect sensors are less common than inductive ones and tend to only be found on high-performance cars. Hall effect sensors work by using a magnet to generate a signal which is then sent to the ECU where it helps determine the position of the camshaft.
Both inductive and Hall effect sensors are accurate and reliable, though inductive ones tend to be more affordable due to their cost-saving advantages.
While more costly, Hall effect sensors offer some advantages over inductive ones like not being affected by electromagnetic interference (EMI) – making them ideal for environments with a lot of EMI such as welding equipment.
Symptoms of a Bad Camshaft Position Sensor

The camshaft position sensor’s job is to measure the rotations and position of a camshaft. This data helps the engine control module (ECM) determine when spark and fuel should be ignited for maximum engine efficiency.
Starting up an internal combustion engine begins with its camshaft opening the intake valve, allowing air and fuel into the combustion chamber. With such an essential role in vehicle operation, it’s critical that this sensor works properly.
But, like all parts, the camshaft position sensor tends to fail too. So, here is a list of symptoms of a bad camshaft position sensor:
1. Check engine light will ignite

One of the first signs that your camshaft position sensor may be malfunctioning is a check engine light. If the ECM detects something amiss with the sensor, this light will illuminate your dashboard.
Here are some codes related to camshaft position sensors:
- P0340 – Camshaft position sensor circuit malfunction.
- P0341 – Camshaft position sensor circuit not within specifications.
- P0342 – Camshaft position sensor ”A” circuit low.
- P0343 – Voltage problem with the camshaft position sensor.
- P0344 – Camshaft position sensor ”A” circuit intermittent.
- P0345 – Camshaft position sensor circuit malfunction.
- P0346 – Incorrect voltage associated with a Camshaft position sensor.
- P0347 – Camshaft position sensor A circuit low input (bank2).
- P0348 – Camshaft position sensor detected a higher voltage reading.
- P0349 – Camshaft position sensor in a bad position.
2. Car takes longer to start than usual

For your car’s engine to run optimally, it needs three things: air, fuel, and spark. The camshaft position sensor signals the engine computer (ECU) when to fire up the spark plugs; if it is malfunctioning, your ECU won’t know when to ignite them properly and this could result in increased engine startup time or illuminate your check engine light.
If your car is having issues starting or running correctly, it could be an indication that your camshaft position sensor needs replacing. These inexpensive sensors are relatively common, so it’s a wise idea to get them checked out.
3. Bad fuel economy


If the camshaft position sensor is malfunctioning, it can cause the engine to run inefficiently and result in poor fuel economy. Decreased fuel economy is one of the most common symptoms associated with an issue with this sensor.
The ECM is responsible for controlling fuel
If you suspect that your camshaft position sensor could be contributing to poor fuel economy
4. Rough idle


A malfunctioning camshaft position sensor can lead to a rough idle, as it deprives the engine of essential information it needs for smooth running. Though the engine will try its best to compensate, there’s only so much it can do and this leads to an uncomfortable idle.
In extreme cases, an incorrect camshaft position sensor may even cause your engine to stall altogether!
Due to inaccurate camshaft data from the sensor, the ECM will fail to command a spark during power stroke when both intake and exhaust valves are closed, preventing proper combustion.
Without this spark, vibrations or rough idle
5. Car not accelerating as before


A malfunctioning camshaft position sensor will result in poor acceleration, as the signal it sends to your engine’s computer is delayed. This causes lean conditions – not enough fuel being delivered to cylinders – which reduces power and makes acceleration difficult.
If you believe your camshaft position sensor is causing your vehicle’s poor acceleration, take it to a mechanic who can diagnose the issue and replace the sensor if necessary.
6. Failed emissions test


The camshaft position sensor is an integral component of the engine management system. It helps the electronic control unit (ECU) determine the proper timing for igniting the fuel-air mixture in cylinders. If this sensor malfunctions, it can cause your engine to run poorly and fail emissions tests.
Camshaft position sensors can become damaged due to age or wear over time. One possible explanation is simply age; over time, the sensor becomes corroded or damaged from heat and vibration.
Another possibility is something interfering with its signal, like dirt or oil buildup on its surface. Finally, it could be that the wiring harness or connector for the sensor has become damaged.
If you suspect your camshaft position sensor may be malfunctioning, it is essential to have it evaluated by a mechanic immediately. They can connect a diagnostic tool to your car’s computer and run some tests in order to confirm the issue.
7. Difficulties in shifting gears


Your car’s transmission plays a vital role in its overall performance, and the camshaft position sensor plays an essential role. If your sensor malfunctions, you could experience delayed shifts, hard shifts
If you’re experiencing any of the following issues with your car’s transmission, it is imperative to have it diagnosed and repaired promptly. Ignoring the issue will only make matters worse and could eventually result in complete transmission failure.
So if you suspect your camshaft position sensor might be to blame for your transmission troubles, don’t wait – get help today!
8. Your car may be smelling of unburnt fuel
A malfunctioning camshaft position sensor can lead to the smell of unburnt fuel in your vehicle’s exhaust, as it causes the engine to run too lean. When this occurs, all of the fuel in the cylinders isn’t burned off – leaving behind an unpleasant odor.
If you detect this smell, have your vehicle checked by a mechanic immediately; while fixing this minor issue should not go overlooked, left untreated it could result in major engine damage.
9. Engine stalling


Engine stalling occurs when your engine stops running due to a loss of fuel or air. It can be caused by many things, but one common culprit is an unresponsive camshaft position sensor. Other potential causes include an inefficient ignition system, damaged spark plugs
If your car’s ignition system is electronic, the camshaft position sensor is an essential piece of equipment. This sensor signals to the ignition system what position the camshaft is in so it can fire spark plugs at precisely the correct time. If not working properly, however, you may experience engine stalling.
10. No start at all


A malfunctioning camshaft position sensor can result in a no-start condition for your vehicle. The ECM, or engine control module (ECM), receives information regarding the position of the camshaft relative to the crankshaft through this sensor.
The ECM uses this information to sync fuel injection and ignition timing. If the camshaft position sensor is malfunctioning, it could result in an engine no-start condition. While other causes of a no-start may exist, a malfunctioning camshaft position sensor is one of the most frequent culprits.