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P0340 code (symptoms, causes and how to fix it)


At one time or another, almost all drivers will experience the sudden arrival of an engine warning light. For many, such an event can cause some level of anxiety, considering the upcoming costs of upcoming repairs.

In many cases, concerns about check engine problems tend to peak when the trouble code associated with this light appears to be complex in nature. An example of this is DTC (diagnostic trouble code) P0340, which is related to the camshaft position sensor circuit.

Although the nature of this DTC often discourages the avid hobbyist from tackling these types of repairs, these problems are rarely as difficult to remedy as you might think. In most cases, one can easily fix DTC P0340 and perform all the basic repairs in one night.

Read on to learn more about the cause of the P0340 trouble code as well as what to do, if you encounter this DTC at some point in the future.

What does the P0340 code mean?

P0340 OBD-II Trouble Code Description

Camshaft position sensor “A” circuit malfunction

At any given time, a vehicle’s ECM (Engine Control Module) monitors a multitude of sensors with the goal of achieving optimal combustion efficiency. However, each of these sensors, along with their associated circuitry, must be in good working order for each to function as intended.

For DTC P0340, a vehicle’s ECM has determined that the data provided by the vehicle’s camshaft position sensor is unreasonable. As a result, the ECM turns on a check engine light to illuminate the problem at hand.

Modern internal combustion engines rely on precise engine timing data to optimize various operational functions. The most critical of these functions involves ignition timing and fuel injection, both of which can be affected indefinitely if inaccurate engine speed signals are sent to the corresponding ECM.

Many modern vehicles rely on the signal from their engine’s camshaft position sensor as the primary source of all engine speed data. Although most ECMs record data attributed to the engine crankshaft position sensor, this method of data acquisition is often considered less accurate than that provided by the camshaft position sensor.

While some vehicles will lose crankshaft position sensor readings in the event of a camshaft position sensor failure, others will not. If the latter occurs, the vehicle’s handling will be affected.

Related codes: P0010, P0011, P0012, P0013, P0014, and P0341

Code P0340 Symptoms

stall the engine

The symptoms associated with DTC P0340 often vary between vehicle makes and models. However, many of these properties are fairly standard, regardless of the vehicle in question.

These are some of the most common symptoms of DTC-P0340.

  • Cannot start engine/difficulty starting
  • stable intermittent
  • irregular or irregular
  • fail from time to time
  • check engine light

Causes of code P0340

Defective camshaft position sensor

A P0340 trouble code may be the result of a number of underlying problems. Determining the exact cause of such a code, as it relates to your specific vehicle, will require a complete diagnosis.

These are some of the most common causes of DTC-P0340.

Is code P0340 serious?

DTC P0340 is considered quite serious due to the long list of possible waste problems that can often occur. In the most severe cases, underlying problems with the P0340 code can cause a stall or no-start condition, which would quickly render a vehicle inoperable.

The crash issues associated with P0340 can also be a safety hazard. If a vehicle stops at any speed while in operation, a number of dangerous circumstances can easily arise. These concerns are only exacerbated when frequent interstate travel is common.

In all cases, the root cause of the P0340 diagnostic trouble code should be addressed as soon as possible. If you are not comfortable doing these repairs yourself, or if you do not have time to do so, you should make an appointment with a reliable auto repair center as soon as possible.

How to fix

Best vehicle diagnostic scanner

The following steps will help you accurately diagnose the root cause of your vehicle’s P0340 trouble code. As always, the vehicle manufacturer’s specific service documentation should be consulted to find the most accurate ways to diagnose faults specific to your particular vehicle.

#1 – Find additional codes

Before beginning the diagnostic process, it is important to check for additional trouble codes, using a scan tool. If additional codes are found, each must be fully diagnosed.

#2 – Inspect the wiring in the camshaft position sensor circuit

Your engine’s camshaft position sensor wiring should now be carefully inspected. This wiring should be checked for breaks or scratches, all of which can occur along any exposed point in the circuit. If such damage is observed, proper repair should be given priority.

#3 – Inspect the camshaft position sensor connection

Now you need to inspect the camshaft position sensor connector on your engine. A quick pull test will ensure that this connector is tight. Additionally, all pins on this connector should be checked for damage or corrosion.

#4 – Check the camshaft position sensor signal

If DTC P0340 persists, the signal associated with the affected camshaft position sensor should be checked. This can be done with most high-end scan tools or with an oscilloscope. If irregularities are observed in the square wave signaled by the sensor, it is recommended to replace the sensor.

#5 – Check Crankshaft Position Function

In some cases, an engine ECM will rely on a comparison between the crankshaft position sensor signal and the camshaft position sensor signal to validate the functionality of each sensor.

If the affected engine’s camshaft position sensor was tested correctly, the crankshaft position sensor should be tested in the same manner. Additionally, any irregularities during this test will require the replacement of the crankshaft position sensor.

#6 – Check for ECM/PCM Updates

If problems persist with DTC P0340, suspect the vehicle’s ECM or PCM. Before criticizing such a module, it is important to ensure that all associated software is up to date.

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