7 Symptoms of a Bad Camshaft Position Sensor (and Replacement Cost)

Last Updated on May 7, 2021

The camshaft position sensor (CMP) is just one of the many electrical parts found in a vehicle. We’ll go over what this component is, the symptoms of a bad camshaft position sensor, and what you can expect its replacement cost to be when it’s faulty.

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A lot of people confuse the camshaft position sensor with the crankshaft position sensor because they sound similar. But there’s a big difference between the two as they perform different functions in the vehicle and have different symptoms when something goes wrong with them.

Related: Single Overhead Cam Engine vs Double Overhead Cam Engine

What is a Camshaft Position Sensor?

what is a camshaft position sensor

Every modern-day vehicle has a camshaft position sensor. This sensor is a very important part of any vehicle because it helps ensure that the engine is running properly.

You may have trouble spotting the sensor when you look under the hood of your car. Usually, different car manufacturers will have their own unique spot near the engine for mounting the sensor. You may find it either in back of the cylinder head, in the lifter valley of the vehicle, or next to the engine block.

The purpose of a camshaft position sensor is to determine the position of the camshaft as it relates to the crankshaft. This data is then sent to the powertrain control module (PCM) for use with fuel injector and/or ignition system control.

Common Symptoms of a Faulty Camshaft Position Sensor

#1 – Check Engine Light Illuminates

check engine light on

When your camshaft position sensor is faulty or starts having issues, the first thing you should notice is that your “Check Engine” light comes on in your dashboard. Obviously, the “Check Engine” light could indicate a variety of problems and not necessarily a bad camshaft position sensor.

In this case, you should either use an OBD2 scan tool to retrieve the stored diagnostic trouble code(s) in your car or have a professional mechanic perform an inspection of the vehicle’s engine control module to see what is going on. They too will scan this module in order to receive a series of error codes which will indicate to them what the real problem is.

Please do not ignore or postpone scanning your vehicle or getting it inspected when your Check Engine light turns on or else your engine could end up getting seriously damaged. The engine could even end up failing altogether, which means you’d end up having to either rebuild or replace your engine.

Related: P0010 Code, P0011 Code, P0013 Code, P0340 Code

#2 – Ignition Problems

bad ignition coil symptoms

As a camshaft position sensor starts having problems and weakens, the transmitted signal to the car’s computer weakens as well. This means the eventually the signal is so weak that it will not allow the car to start since there will be no spark from the ignition.

#3 – Car Jerking or Surging

car jerks when accelerating

If you are driving your vehicle and the camshaft position sensor starts failing, the engine will at times simply lose power and cause your car to jerk or randomly surge forward.

These are both a result of an improper amount of fuel being injected into the cylinders since the PCM is getting incorrect information from the camshaft position sensor.

#4 – Engine Stalling

rough idling

An even worse scenario than not being able to start your car is that your engine actually shuts off or stalls while you’re driving because the fuel injectors aren’t being told to inject fuel into the engine cylinders.

We probably don’t need to tell you how dangerous that situation could be.

#5 – Poor Acceleration

reasons and causes of car not accelerating

Aside from jerking, your vehicle won’t be able to accelerate very fast when your camshaft sensor begins to fail. Heck, you’d be lucky to accelerate past 30 miles-per-hour in some cases. The poor acceleration is again due to incorrect fuel delivery by the injectors.

#6 – Problems Shifting 

automatic transmission shifting

Certain models of cars with a bad camshaft position sensor will end up with a locked transmission that stays stuck in a single gear. The only way you’ll be able to get out of that gear is to shut off your engine, wait a bit, and then restart.

This is only a temporary solution and the problem will reappear so replacement of the sensor is necessary as a permanent fix.

Along with this, your vehicle may put itself into “limp mode” which won’t allow you to shift gears or accelerate beyond a certain speed.

#7 – Bad Fuel Mileage

poor gas mileage

This is the opposite of not delivering enough fuel to the engine. In this case, because of an inaccurate reading from a bad camshaft position sensor, more fuel than necessary is injected into the engine which causes your fuel economy to drop.

Camshaft Position Sensor Replacement Cost

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camshaft position sensor replacement cost

To replace a camshaft position sensor, you can expect to pay anywhere from $95 to $200. Parts alone will run about $25 to $100. Labor costs will be in the range of $70 to $100 for professional replacement.

Expect to pay more if you have a luxury vehicle or are having your local car dealership perform the replacement. There will also be additional fees and taxes added on to these costs as well.

Can You Replace a Camshaft Position Sensor Yourself?

Yes. This is one of those jobs that almost anyone can do and is an easy way to save yourself the minimum labor fee (often close to $100) that a repair shop or dealership will charge you. It should take about 5-10 minutes to replace it.

How to Replace a Camshaft Position Sensor

  1. Disconnect the negative battery cable.
  2. Locate the sensor. It’s usually on the top, front, or rear part of the engine. It will likely have a 2-3 wire connector attached.
  3. Release the tab on the sensor to disconnect the wires from the sensor.
  4. Remove the mounting bolt which attaches the sensor to the engine. It’s usually an 8mm or 10mm bolt.
  5. Pull the sensor off with a slight twist.
  6. Apply a bit of engine oil to the o-ring of the new senor.
  7. Install the new camshaft position sensor and secure with the mounting bolt.
  8. Reconnect the wire connector to the sensor.
  9. Reconnect the negative battery terminal.


When you bring your vehicle in to a dealership or repair shop for routing service or a tune-up, the mechanic won’t normally inspect the camshaft position sensor if they are not asked to.

If you have experienced any of the warning signs listed above, let them know you think it may be the camshaft position sensor. This will allow them to quickly inspect the camshaft position sensor to determine whether it’s causing these problems.


82 thoughts on “7 Symptoms of a Bad Camshaft Position Sensor (and Replacement Cost)”

  1. I had my camshaft sensor replaced recently, but it still has an epc light flashing on when im hitting the gas and the engine still shakes around. Could this be a wiring problem? what could be the problem if its still not working but my P0341 code still pops up and is still having bad camshaft sensor problems.

    • It could be wiring, a bad ground, or a poor connection in the camshaft sensor connector on the wiring harness side.

      You can do a visual inspection of wiring leading up to the camshaft sensor. Next try the wiggle test to see if the condition improves or worsens when you physically move the wiring harness around. If those tests are inconclusive, you may have to bust out a multimeter to do a bit of electrical diagnostic work.

  2. I have a Discovery Sport 2.2L diesel, the 2015 model. My vehicle shakes some times in the highway but after a while it goes away. Wondering it’s a bad camshaft sensor.

    • Did the vehicle throw a code that led you to believe it was a bad camshaft sensor? If so, what was the code?

      Shaking on the highway could be a lot of things. It’d be best to take the vehicle to a shop to have it inspected.

  3. I replaced the can shaft sensor because the code P0340 (1) came up. The light came back on and stays on. The vehicle runs fine. Should I check the 02 sensor, the Catalytic Converter, or get the computer checked. 2002 Mercury Mountaineer.

    • Check the wiring around the cam sensor if you can. It’s possible there is a short, maybe a broken wire or some worn insulation that exposes the bare metal of the wire.

    • No, it probably wouldn’t. I would say in the majority of cases the oil pressure light would not illuminate for a bad cam sensor.

  4. Hi. I got a Audi A3 sport 2005, when the engine in cold the car start normally ,when the engine in hot is starting little bit harder ..also I got engine light on…is the sensor problem ??

    • I doubt this would be caused by the camshaft position sensor. Vehicles often change their air fuel ratio for a cold start vs a hot one. You could try looking up the function of different sensors on your vehicle and see if one controls the hot start fuel ratio. You should be able to find this information in the factory service manual.

      Another possible cause of hot start issues is a low compression ratio. A compression test will tell you if you have low compression.

  5. Hi I have a 93 Pontiac firebird an I replaced my starter plugs wires u name it but my car with try to start but won’t dull start an run I know its not my starter cause I’ve replaces it an the fuel pump I’m just out of ideas on what could be making it not run can u help me ?

    • First, try to narrow down the problem to see if it’s fuel, spark, timing, or compression. Have the car scanned for check engine light codes to see if that narrows down the problem. If you see a code for a camshaft or crankshaft position sensor, start there. Perhaps the sensor went out or there is a wiring issue leading up to the sensor.

    • Could be a wiring issue like a short or bad ground. I would do some electrical diagnosis to see if you can find a problem further up the wiring harness. See if the insulation is damaged or worn away anywhere, or if you notice any corrosion on any terminals or ground straps. Make sure your ground straps are clean and tight.


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