A P0340 Code gets stored in the engine control module when it got a faulty signal from the Camshaft position sensor.

There are some possible causes of this, and in this article, you will learn how to diagnose it properly.

P0340 Definition

Camshaft Position Sensor – Circuit Malfunction

What does P0340 mean?

A P0340 means that there is a malfunction in the circuit of the Camshaft Position Sensor A.

This can mean that there is a faulty camshaft position sensor or the wires on the way to the sensor. Just don’t get confused with a bad camshaft timing with this trouble code.

P0340 Symptoms

The most common symptom you will have with the P0340 code is a hard starting condition. The car engine uses the camshaft position sensor, especially when the engine is about to start.

How serious is the P0340 Code?

Severe – The engine uses the camshaft position sensor quite much for ignition timing and fuel supply.

If you do not fix the problem, you might get stranded in the morning when you start the car. Internal engine damages may also occur because of the wrong ignition timing and fuel supply that might happen.

Causes of the P0340 Code

The most common cause of the P0340 code is actually a faulty camshaft position sensor. There can also be any problems with the wirings to the sensor or corrosion in the camshaft sensor connector plug.

  • A faulty camshaft position sensor
  • Faulty camshaft position sensor wirings
  • Corrosion in the camshaft position sensor connector plug
  • Weak battery
  • A Defective engine control unit

What repairs can fix the P0340 code?

  • Replace the camshaft position sensor
  • Clean the camshaft position sensor connector plug
  • Repair wirings to the sensor
  • Charge your car battery and clear codes
  • Replace engine control module

Common P0340 Diagnostic mistakes

One common mistake many people make when they see the P0340 is panicking over a faulty timing chain or belt. The P0340 clearly states that there is an electrical problem in the circuit to the camshaft position sensor.

Therefore the P0340 trouble code is not caused by a faulty camshaft timing.

How to diagnose the P0340 Code

  1. Connect an OBD2 scanner and look for any related trouble codes. You can try to remove the code to see if it directly comes back.
  2. You do now have two options if the code came back. Measuring the camshaft position sensor is quite difficult if you are not used to it. You can either measure it by finding the right ohm values or checking the signal with an oscilloscope, or you can just replace the camshaft position sensor A. Camshaft sensors are often quite cheap and easy to replace. So you decide if you want to take the risk. After all, the most common problem with this trouble code is actually a faulty camshaft sensor.
  3. If you have measured the sensor or replaced it and the trouble code still comes back – you need to measure and inspect the wirings between the engine control module and the sensor. Unplug the sensor and the engine control unit. Check for any shorts between the wires or shorts to the ground.
  4. If the wirings seem to be OK, there is only one thing left that can be the problem – A fried engine control unit. These are really expensive and require special coding after replacement, so you should really ensure that the engine control unit is the problem. You can measure the 5v+, ground, and signal, which should come out from the engine control unit if you are experienced.