OBD-II Trouble Codes

P0340 Code: Camshaft Position Sensor “A” Circuit Malfunction

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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.

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:

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:

How to Diagnose the P0340 Code

When it comes to OBD-II codes, diagnosis isn’t always a straightforward process. It can be difficult to pinpoint the exact cause of most trouble codes as there can be a variety of potential causes—and you can expect the same with a code P0340.

For an idea of how to troubleshoot the code, check out the videos below:

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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Staff Writers

In the Garage with CarParts.com is an online blog dedicated to bringing DIYers and devoted car enthusiasts up to date with topical automotive news and lifestyle content. Our writers live and breathe automotive, taking the guess work out of car repairs with how-to content that helps owners get back on the road and keep driving.

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