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

Last Updated on September 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, P0016 Code, P0340 Code, P1345 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.

Tip

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.

 

107 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.

    Reply
    • 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.

      Reply
    • You unfortunately could be facing slipped timing. Since you called it an EPC, I’m guessing you have an Audi? VW?
      If so, chances are you’re looking at a zero-clearance engine, which in turn equals bent valves and a trashed head and piston(s). The extent of damage to the valves and pistons will be determined by how many teeth your timing chain/belt slipped. More than 2 generally results in the engine being damaged so badly it can’t run, but one or 2 teeth can result in the engine running very rough, if at all.
      Its a possibility you’re getting a bad sensor code because the cam-ps & crank-ps are reading differently due to the timing physically being off.

      This is just a possibility. I recommend having the actual timing itself checked, especially if you’ve not replaced the chain/belt in the last 60k-75k miles.

      Reply
  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.

    Reply
    • 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.

      Reply
  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.

    Reply
    • 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.

      Reply
    • 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.

      Reply
  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 ??

    Reply
    • 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.

      Reply
  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 ?

    Reply
    • 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.

      Reply
    • 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.

      Reply
  6. My 2018 Ford Focus suddenly the oil pressure light and engine light came on and codes says cam sensor problem. didn’t know it would make the oil pressure light come on.

    Reply
    • I’m not sure. Could be two separate issues, or an electrical issue that causes both lights to come on. More diagnostic work is needed.

      Reply
  7. Sir ,my car Passat 2.0 non turbo it some time fail to accelerate on the gas pedal,the car stall…pls what can be the possible cause…thanks

    Reply
    • Make sure all basic maintenance is done, such as replacing the spark plugs and wires, changing the engine air filter, etc. Are there any codes associated with that slowness/stalling?

      Reply
  8. Been having check engine light for a few years 2011 chysler 300 cam shaft bank 1, changed all the sensors , crankshaft senor also, did a tune up. At first maybe once a year it would start up funny, slow, and the light comes out then after i think it is 4 starts it goes away. Now it does it maybe once a week. Took it in to get checked, They thought it was the connector but said it was good and wiring was good. They did a cam phaser scan and was hoping that was the fix. Car runs fine then a week later a funny start and check engine light back on. IT does sound like a loud rattling noise when I start my car comes out. Almost like a lawnmower. I am going to take it back to get looked at.. they said it is a process of elimination. So on to the next step.

    Reply
    • Yeah, sounds like they are on the right track with that diagnosis. Describing it as a “lawnmower” makes me think there may be an exhaust leak. See what the shop says, I’d be interested to hear the verdict once they find the problem.

      Reply
      • Sean, I should of stated that the lawnmower noise has been happening for years. My dad asked me one time If I leave the A/C on when I turn off the car. I said no I turn everything off, A/C, Radio, off. I did have my catalaic converter changed out a few months ago. The code came out for it and changed it. It had melt the sensor.

        Reply
    • Sounds like you might have a vacuum leak if you have high RPM. You could do a smoke test to rule that out.

      So, are you having both low RPM and high RPM? When does each occur?

      Reply
  9. I’m having issues with my car. About a week ago I took it in to local garage and they said to me it was both my camshaft and crankshaft sensor that would need replacing. I told them I’ll think about it as I thought at the time maybe its best to sell the car because of the expenses I have spent on the car previously. However now, When I turn the engine on, all I can smell is smoke, and its also visible from the exhaust. I’m worried I can’t make it to a garage. What could I possibly do? I have tried taking it for a drive but its so much worse than a week ago.

    Reply
    • Sounds like you shouldn’t be driving it. You can try selling it but chances are you won’t get as much for it if the vehicle is running poorly or not at all. I would take it back to the mechanic to have it repaired. Did they give you a cost estimate on the repair?

      Reply
  10. 2013 Mini Cooper check engine light is on. OBD says P0015. Replaced sensor check engine light still on. Car has no problem starting, running and accelerating. Why is check engine still on.

    Reply
    • Sounds like an issue with the variable valve timing, and I think you replaced a perfectly good sensor.

      Something is causing the VVT to respond differently than the ECU intends. You’ll have to do a bit of digging to see if the problem is electrical in nature (bad ground, short, etc) or an issue with oil pressure in the VVT system (possibly a bad solenoid or clogged passage). Good luck on your search.

      Reply
  11. 2014 Nissan Altima, changed camshaft sensor as the code stated but the engine light still shows up after a few kms and stays there.

    Suggestions?

    Reply
    • I’m assuming the check engine light is still for the camshaft position sensor?

      You’ll have to do a bit more diagnostics to narrow down the problem. Could be electrical (like a bad ground), could be a timing issue with the timing chain or timing chain tensioner. Someone will need to put their hands in the engine bay to give you more info, though.

      Reply
  12. I have a 1996 Toyota corolla 1.6 engine. the check engine light is on. the car will crank but not start unless I spray starting fluid in it. then it runs as long as I keep the gas pedal depressed. but when I take my foot off slowly and get to almost low idle it cuts off again and will not start unless more starting fluid is sprayed in the throttle body. I think it is the cam shaft position sensor. The sensor is built into the distributor

    Reply
    • Scan for codes and that should tell you pretty quickly if it’s the camshaft position sensor.

      When the car runs, how does it sound? Is it rough, like it’s struggling to stay running? That may indicate a timing issue, or possibly a big vacuum leak that is making it run way lean.

      You know you have spark because the car will run when you spray starting fluid. I would look at fuel and timing next. Make sure the injectors and fuel pump are working. Can you hear the fuel pump prime when you turn the key on with the engine off?

      Good luck, let me know how it goes.

      Reply
  13. very helpful thread. especially note : i had random engine misfire, blinking MIL and P0300 random engine misfire on chevy 3500 express van, no rough idle, hesitation, lack of power or fail to start . i replaced crankcase position sensor which stopped flashing MIL and code. : then w/in 100 miles, van started to throw CAMSHAFT position sensor code with a steady MIL lite. after new CkKPos went in , engine ran well, just like before but now was throwing steady MIL at all rpms over 2200 especially at 65+ mph highway speed and going up hills. NOTE if you need to replace CkC Pos sensor due to age, do yourself a favor and replace the old CAMSHAFT sensor at the same time.

    Reply
  14. I have a 2009 Audi Q5 with 3.2L V6 and had the driver side upper timing chain and tensioner changed in June 2020 when it had 199,250 km (125000 miles) on it. Then 4200 km later in Dec 2020 the engine light came back on and it now had code P0018 camshaft/crankshaft correlation error on bank 2, sensor A which is intake camshaft. As I have bought another vehicle and need to sell this one, I took it back yesterday to the ex-Audi tech who changed the chain and tensioner on driver upper side, and he swapped out my camshaft position sensor with 1 from same 3.2L audi engine (used) he had on floor, and it seems better since yesterday- 10 drives and no light where usually light comes back after 2-3 drives. Despite no light, code P0018 still set again though after he cleared it yesterday, so am wondering if I should try a brand new CMP sensor or is it the other 3 chains or the camshaft gear that might be damaged. He changed the 1 chain without removing engine, as he took apart the old chain and followed it with new chain which he had the tool to relink new chain. It has been very quiet ever since, but seems to have a bit less power at low rpm unless I use sport mode. Your help appreciated. Thanks in advance

    Reply
  15. I have a Nissan teana j30, V6 engine.
    It would switch off when in motion leaving the dashboard on, fail to start there and then unless after some minutes. The dashboard has an engine check light.
    Had it scanned and showed camshaft position sensor B1 being faulty but the engine has two camshaft position sensors. 1. Will it be okay to replace both?
    2. Will the problem be solved completely?
    3. What causes faulty camshaft position sensors?
    4. What will be other possible problems I should anticipate after fixing this?

    Reply
    • 1. It is okay to replace both, worst case you lose money by replacing a working sensor.
      2. Hard to say. Often the problem is not the sensor itself, but a timing issue that triggers the camshaft or crankshaft sensor code. This could be an issue with the timing belt/chain, tensioner, or variable valve timing (VVT) system.
      3. Depends on the type of camshaft sensor. Some are mechanical and wear over time. Others are electrical and short out. This could also be a symptom of a bad ground somewhere else in the wiring.
      4. I’m not sure I understand the question; fixing the problem shouldn’t cause another. If you replace the sensors and the problem persists or a new one surfaces, the camshaft sensors were probably not the root cause of the problem.

      Reply

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