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A P0340 error code can be a serious issue that requires immediate attention, as the underlying cause can lead to engine damage the longer you continue to use the vehicle.

If your car is triggering a P0340, read our comprehensive guide below to learn more about the causes and symptoms associated with this OBD-II code, and to find out how to diagnose and fix the problem.

image of camshaft position sensor, which could cause a P0340 code if its signal is disrupted
The camshaft position sensor calculates the speed at which the camshaft rotates. Disrupted signal from the sensor may cause the PCM to log a P0340 code.

What Does Code P0340 Mean?

The OBD-II diagnostic trouble code P0340 indicates a “Camshaft Position Sensor “A” Circuit Malfunction.” It covers the entire circuit attached to the aforementioned sensor, such as the electric wiring and the powertrain control module (PCM). Thus, replacing the sensor will not always resolve the issue.

The camshaft position sensor calculates the speed at which the engine’s camshaft rotates. It also keeps track of the shaft’s precise position during rotation. It signals the PCM, which uses the sensor data to set the timing for the ignition and fuel injection systems.

Disrupting the signal from the camshaft position sensor throws off the engine’s precise timing and can cause performance problems, such as misfires and sub-optimal fuel-to-air mixtures. The PCM will log a P0340 code and activate the Check Engine Light to warn the driver that something went wrong.

The P0340 code is a generic powertrain code. It applies to all makes and models of vehicles built during or after 1996. Specific models may need special steps during diagnosis and repair of a fault in their camshaft position sensor’s circuit.

A similar code is P0335, Crankshaft Position Sensor “A” Circuit Malfunction. Like P0340, P0335 also warns about a problem in a sensor’s electric circuit. The difference is that P0335 covers the crankshaft that converts engine power into forward motion, while P0340 involves the camshaft that controls the intake and exhaust valves.

A P0340 code spells bad news for any vehicle. Drivers may find it difficult or impossible to start the engine because of the resulting engine performance problems. If they persist in operating the vehicle, they may lose power while on the road. Also, ignoring the camshaft position sensor issue for too long can even damage the engine, leading to a much longer and more expensive repair job.

Given these drawbacks, drivers should avoid using a vehicle suffering from a problematic camshaft position sensor circuit. Instead, they must determine the root cause of the P0340 trouble code and fix it as soon as possible.

While people with sufficient DIY mechanical skills can find and fix many of the issues, the surest option remains taking the vehicle to an auto repair shop.

Users have reported P0340 for the following makes: Ford (especially on a Ford F-150), Nissan, Dodge, Chevrolet, and Jeep.

What are the Possible Causes of the P0340 Code?

The most common causes behind the disruption of the signal from the camshaft position sensor to the PCM include:

  • Failing or defective camshaft position sensor
  • Circuit problems (e.g., damaged wiring, loose connections)
  • Errors in the powertrain control module (somewhat rare)
  • Damaged camshaft position sensor reluctor wheel
  • Problems with internal engine timing components

Many drivers immediately replace the camshaft position sensor once they receive the P0340 code. But as you can see by looking at the list of potential causes above, there are several other reasons that could hamper the device’s signal.

Wiring issues feature prominently in many incorrect diagnoses of the P0340 trouble code. Likewise, the problem in the camshaft position sensor’s circuit may stem from the issues with internal engine timing components.

Check engine light turned on
The Check Engine light should illuminate if the PCM logs code P0340.

What are the Common Symptoms of the P0340 Code?

A vehicle that has been diagnosed with a P0340 code shows several symptoms linked to the problematic circuit:

  • Check Engine Light warning
  • Engine experiences hard starts or cranking without starting
  • Engine hesitates or stalls while running
  • Engine dies and refuses to restart
  • Rough running, misfiring and/or lack of acceleration

How to Diagnose the P0340 Code

P0340 must not be ignored. You need to check all potential causes to pinpoint the exact problem. Consider taking your vehicle to a professional automotive technician if you don’t have enough DIY auto repair experience and skills. The video below could give you a better idea of the diagnostic procedure if you’re still interested in checking your own vehicle.

How to Fix the P0340 Code

As with many of these OBD-II trouble codes, you won’t find a “magic bullet” fix for a P0340. If there is more than one potential cause, you’ll also have more than one possible solution to the problem. Since the P0340 code can be caused by one of several underlying issues, there are different fixes—one of which, as mentioned, could be camshaft position sensor replacement, although of course this isn’t always the case.

You’ll need to diagnose the code accurately and pinpoint the cause, as outlined in the video above, then perform the appropriate repairs.

Also, as all vehicles are different, make sure to consult the factory repair information when troubleshooting and repairing diagnostic trouble codes.

Repair manuals, such as those from Chilton, are useful, but an ALLDATA subscription is even better. ALLDATA has single-vehicle subscriptions for DIYers that provide detailed factory repair information.

Other Notes About Code P0340

Like any other vehicle part, the electric circuit connected to the camshaft position sensor can develop malfunctions from improper care, rough usage, or general wear and tear. The resulting P0340 trouble code can appear in any vehicle, even from trusted brands like Ford and Nissan.

When the OBD-II scanner shows a P0340 code that denotes a bad camshaft position sensor circuit, bring the affected vehicle to an auto repair shop as soon as possible. Otherwise, continuous operation will not only prove difficult because of poor engine performance from misfires, but it can eventually harm the engine.

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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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Comments

  1. mmb says

    Car was running fine, but at oil change the dealor noticed mild oil leak. They fixed that (valve and seal) and on driving it home from repair place, engine light came on, and per OBD check it is this code. Seems odd that there were not issues before car was being worked on for something else. Is it possible circuit or other could have been damaged while in for other repair?

  2. mikejca says

    Have a 2004 avalanche with the 5.3 in it. Getting CMP high voltage code. While checking the wire harness for the sensor, I discovered the ref low (ground) had 21 volts coming from it. The power had 10.5 volts. I;m thinking it is my ECM/PCM. Bu need to check entire harness for any exposed wiring. What do you think?

  3. Joe Uu says

    I have a 2010 Dodge Charger SXT I picked up for a really nice price. The car wouldn’t start so I changed out both fuel pumps because the passenger side was dead. Tried to start her up and still no luck so I changed the sparkplugs and the coil packs. Still nothing. I tested for spark, fuel, compression I even bought another ECM, ). Flashed to my vin. Had someone come out and reprogrammed the key. More then triple scanned the car with my OBD2 also double checked the PCM ( no visible damage to any wires) and just yesterday it threw the code P0340. I changed the sensor and still the same. I’m just up in the air on where to start. Should I run some test on the sensor with a multi meter. And do I have someone crank the car over while testing? Any help is greatly appreciated. Thanks

    • says

      Hi Joe,

      Your car has a timing belt. What were the results of your compression test? Does the engine crank normally or does it turn over faster than normal? It’s possible the timing belt has jumped time.

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