Symptoms of a Bad Camshaft Position Sensor: What to Look Out For


If you’re experiencing problems with your car, one of the things that you may want to check is the camshaft position sensor. This component is responsible for sending signals to the engine control unit, and if it’s not working properly, it can cause all sorts of issues.

In this blog post, we will discuss the symptoms of a bad camshaft position sensor and what to do if you think yours may be faulty.

Symptoms of a bad camshaft position sensor include a check engine light with a P0340 – P0349 trouble code, the car taking longer to start than usual, bad fuel economy, rough idle, car not accelerating as before, failed emission test, difficulty shifting gears, a smell of unburnt gas, engine stalling or no start at all.

What Is The Purpose Of Camshaft Position Sensor

The Camshaft Position Sensor is responsible for monitoring the position and rotational speed of the camshaft. It relays this information to the engine control unit, which uses it to adjust the timing of the ignition and fuel injection system. This ensures that the engine runs smoothly and efficiently.

There are two types of camshaft position sensors in cars, the inductive and Hall effect sensors. The inductive sensor uses an electromagnetic field to produce a signal, while the Hall effect sensor uses a magnet to produce a signal. Both types of sensors are used to measure the position of the camshaft.

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The most common type of camshaft position sensor is the inductive sensor. Inductive sensors are used on almost all modern vehicles. They work by using an electromagnetic field to produce a signal. The signal is then sent to the engine control unit (ECU). The ECU uses the signal to determine the position of the camshaft.

Hall effect sensors are less common than inductive sensors. They are usually only found on high-performance vehicles. Hall effect sensors work by using a magnet to produce a signal. The signal is then sent to the ECU. The ECU uses the signal to determine the position of the camshaft.

Both inductive and Hall effect sensors are accurate and reliable. However, inductive sensors are more common because they are less expensive to manufacture. Hall effect sensors are more expensive, but they offer some advantages over inductive sensors. For example, Hall effect sensors are not affected by electromagnetic interference (EMI). This means that they can be used in environments where there is a lot of EMI, such as around welding equipment.

Symptoms of a Bad Camshaft Position Sensor

Symptoms of a Bad Camshaft Position Sensor

The purpose of the camshaft position sensor is to measure the rotations and position of the camshaft. The ECM uses this data to know when to command spark and fuel for the best engine efficiency. The internal combustion engine starts with a camshaft opening the intake valve and allowing air and fuel to the combustion chamber. Having such an important role, the camshaft position sensor has to be working properly in order for the vehicle to function as it should.

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 symptoms of a bad camshaft position sensor you might be experiencing is a check engine light. If the ECM senses something wrong with the sensor, the check engine light will pop up on the dashboard. Here are some codes related to the camshaft position sensor:

  • 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

A car’s engine needs three things to run: air, fuel, and spark. The camshaft position sensor tells the engine computer (ECU) when to fire the spark plugs. If the camshaft position sensor is not working correctly, the ECU can’t tell when to fire the spark plugs. This will cause the engine to take longer to start. A bad camshaft position sensor can also cause your check engine light to come on.

If you’re having problems with your car starting or running properly, it could be a sign that your camshaft position sensor needs to be replaced. Camshaft position sensors are relatively inexpensive, so it’s a good idea to get them checked out.

3. Bad fuel economy

If the camshaft position sensor is not working properly, it can cause the engine to run inefficiently. This in turn will lead to bad fuel economy. The decreased fuel economy is actually one of the most common symptoms of a bad camshaft position sensor.

The ECM is responsible for commanding fuel when the camshaft opens the intake valve allowing it into the combustion chamber. If the reading is faulty, the ECM will never know when to command fuel at the perfect time resulting in poor gas mileage.

If you think that your camshaft position sensor may be causing your bad fuel economy, then you should take it to a mechanic and have it checked out. It is always better to be safe than sorry when it comes to your car.

4. Rough idle

Symptoms of a Bad Camshaft Position Sensor

A bad camshaft position sensor can cause a rough idle because it prevents the engine from getting the information it needs to run smoothly. The engine will try to compensate for the missing information, but it can only do so much and that’s why you’ll end up with a rough idle. In worst cases, a bad camshaft position sensor can even cause your engine to stall.

Since the ECM is getting faulty camshaft data from the sensor it’s not going to command a spark during the power stroke when the camshaft has both intake and exhaust valves closed allowing proper combustion to occur. If a spark doesn’t occur at this time, it will lead to a misfire resulting in your car having vibrations or in other words rough idle.

5. Car not accelerating as before

A bad camshaft position sensor will cause your vehicle to have poor acceleration because the signal it sends to the engine’s computer is delayed. This will cause the engine to run lean, which means that there is not enough fuel being delivered to the cylinders. This will result in a loss of power and your vehicle will not be able to accelerate properly.

If you suspect that your camshaft position sensor is causing your vehicle to have poor acceleration, you should take it to a mechanic so they can diagnose the problem and replace the sensor if necessary.

6. Failed emissions test

The camshaft position sensor is an important part of the engine management system. It helps the engine control unit (ECU) to determine the correct timing for igniting the fuel and air mixture in the cylinders. If the sensor is not working properly, it can cause the engine to run poorly and fail an emissions test.

There are a few things that can cause a camshaft position sensor to fail. One is simply age and wear. over time, the sensor can become corroded or damaged from heat and vibration. Another possibility is that there is something interfering with the sensor’s signal, such as dirt or oil build-up on its surface. Finally, it’s possible that the wiring harness or connector for the sensor has become damaged.

If you suspect that your camshaft position sensor is failing, it’s important to have it checked out by a mechanic as soon as possible. They can hook up a diagnostic tool to the car’s computer and run some tests to confirm the problem.

7. Difficulties in shifting gears

Your car’s transmission is a vital part of its overall performance, and the camshaft position sensor plays a crucial role in keeping it running smoothly. If your sensor is faulty, it can cause all sorts of problems with your car’s shifting, including delayed shifts, hard shifts, or even no shifts at all. In some cases, a bad camshaft position sensor can also lead to transmission failure.

If you’re experiencing any of these issues with your car’s transmission, it’s important to have the problem diagnosed and repaired as soon as possible. Ignoring the problem will only make it worse and could eventually lead to complete transmission failure. So if you think your camshaft position sensor may be to blame for your transmission troubles.

8. Your car may be smelling of unburnt fuel

A bad camshaft position sensor can cause a smell of unburnt fuel because it can cause the engine to run too lean. When the engine runs too lean, it doesn’t burn all of the fuel in the cylinders, which causes a smell of unburnt fuel. If you notice a smell of unburnt fuel, it’s important to have your vehicle checked by a mechanic as soon as possible. A bad camshaft position sensor is an easy fix and if left untreated, can cause major engine damage.

9. Engine stalling

Engine stalling is when your engine stops running, usually due to a loss of fuel or air. It can be caused by a variety of things, but one of the most common causes for this is a bad camshaft position sensor. Other causes can include a faulty ignition system, a bad spark plug, or a problem with the carburetor.

If your car has an electronic ignition system, then the camshaft position sensor is a crucial piece of equipment. The sensor tells the ignition system what position the camshaft is in so that it can fire the spark plugs at the correct time. If the sensor isn’t working properly, then it can cause engine stalling.

10. No start at all

A bad camshaft position sensor will cause your vehicle to have a no-start condition. The camshaft position sensor tells the engine control module (ECM) the position of the camshaft in relation to the crankshaft.

This information is used by the ECM to synchronize fuel injection and ignition timing. If the camshaft position sensor is not working correctly, it will cause the engine to have a no-start condition. There are other possible causes of a no-start condition, but a bad camshaft position sensor is one of the most common.

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Hi there. I am a certified Automotive Service Excellence (ASE) mechanic since 2018 and a car detailer for 10 years.

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