P0340 Error Code: Camshaft Position Sensor "A" Circuit Malfunction

There are several diagnostic error codes you may encounter during your years of using your car, and the P0340 error code may be one of these codes as it is common. When this code is triggered, it indicates a problem with your car’s camshaft position sensor A circuit, and ignoring this warning code may lead to greater damage to some car components.

In this article, we will dive into understanding the camshaft position sensor A circuit malfunction a little better, then we’ll move on to briefly explain the causes and symptoms of this error code. To close off this topic, we will give a brief guide on how you can diagnose and troubleshoot this code.

What is the camshaft position sensor A circuit?

The camshaft position sensor is an important engine component in modern cars and it works hand-in-hand with the crankshaft sensor to send signals relevant to ignition and injection to the electronic control module (ECM). The camshaft position sensor monitors the position of the camshaft about the position of the crankshaft to send inputs to the ECM.

These inputs sent to the ECM help determine which injection to fire and what the ignition point on a spark plug is.

The P0340 error code doesn’t just refer to a malfunction with the sensor itself but it can also indicate problems with the camshaft, the electric connectors, or other components.

Causes of the P340 error code

Here are some of the possible reasons why this code may be generated on your car:

Faulty camshaft position sensor

With this component responsible for sending signals to the ECM, a malfunction means that it won’t be able to do so or it will send inaccurate information. Inaccurate information sent from the camshaft position sensor to the ECM leads to incorrect fuel injection and ignition processes. 

Open circuit in the camshaft position sensor circuit wiring

The wiring connected to the camshaft and the camshaft position sensor is responsible for sending input to the ECM. An open circuit in the wiring of this component means that there won’t be proper communication between these two components for normal fuel injection and ignition.

A faulty PCM or ECM

The ECM and the power control module (PCM) play a vital role in the functioning of the camshaft position sensor circuit as well as the overall functioning of your car. With these components associated with your camshaft position sensor, a fault in them will interrupt the work of your sensor and trigger this code.

Faulty crankshaft position sensor

With the crankshaft sensor faulty, inaccurate signals will be sent to the ECM or PCM as well just like with the camshaft position sensor and this can affect the accuracy of the ignition timing.

Faulty connector to the camshaft position sensor circuit

When the connector in this component becomes defective, it causes interference in the communication of signals between the camshaft position sensor and the ECM.

Symptoms of P0340 Error code

There are several unusual behaviors you may notice in your car when this code is triggered or when there is a camshaft-related problem.

Check engine light is displayed


The check engine light is a warning light on your dashboard display that usually indicates a problem somewhere in your car. This warning can be an indication of various car issues so we recommend that you do not rely on it alone to diagnose this code.

Engine misfires

Engine misfire happens when one or more cylinders in your car don’t produce power which can lead to loss of power while driving or hesitation when you attempt to accelerate. 

Engine stalls

When your engine stalls, it will feel similar to bucking or jerking to slow the movement or progress of your car. You may also experience difficulty using your steering wheels when there is a fault with your car’s camshaft.

Increased fuel consumption

The camshaft position sensor is made to send information that will aid in fuel injection. When the wrong signal or no signal at all is sent to the ECM, this can lead to your car using for fuel than usual. 

No spark when igniting your car

With the camshaft position sensor is faulty, it sends weak signals to the ECM which affects ignition timing, a fault with this component means that you’ll have trouble starting your car. This lack of ignition can also lead to your engine cranking but not starting. A problem with the crankshaft can also lead to this problem. 

Poor engine performance

Most symptoms (engine misfires, engine stalls, ignition problems) that occur due to a failure in your car’s camshaft are associated with the engine. And with all of them summed up, it results in poor engine performance. It calls for immediate attention else other car components may get damaged as well. 

Troubleshooting P0340 Error Code

Before proceeding to any repairs you want to confirm that your car has a P0340 error code, and besides observing the symptoms present, you want to use a diagnostic tool like an OBD scanning tool.

Here are some of the possible repairs that may be needed when this diagnostic code is generated:

Fixing the camshaft position sensor

The problems associated with this component can be caused by corroded or damaged connector or wiring which means these parts will need replacement if this is the case. Sometimes, the entire camshaft position sensor may need to be replaced if it is damaged beyond repair.

Fixing the crankshaft position sensor

Like the camshaft position sensor, the crankshaft position sensor will also need its wires or harnesses replaced if they are damaged, or in critical conditions, the entire sensor needs to be replaced.

Replace your car’s timing belt


The timing belts are components of the camshaft system and they are used to open and close the camshaft valves. Usually, this belt should be replaced every 6,000 to 100,000 miles but if it comes off, you will need to put it back in place. In situations where the timing belt comes off, a replacement may be needed because it is difficult to get the initial one back in place.

How much does it cost for replacing a camshaft position sensor?

How much you need to pay depends on the make and model of your car. The camshaft position sensor is not a very expensive part, and on average, it will cost $50 to $300 to get a replacement.

The cost of the part itself ranges from $75 to $120 while labor costs can range from $30 to $150. You may need to pay more for both the part and labor costs if you have a luxury car. 


The p0340 error code is related to issues o your car’s camshaft system. After reading this article, you should have learned that this error code narrows down to the camshaft position sensor A circuit malfunction and it can be caused by a faulty camshaft or crankshaft position sensor, poor wiring and connectors of these parts, or a faulty ECM.

You should have also learned a bit about how the function of the camshaft position sensor, the symptoms of this code, and how to fix it. Closing off, we briefly touched on the cost of replacing this part.