P0340 Trouble Code: Camshaft Position Sensor "A" Circuit

Are you experiencing starting issues or a rough idle along with the P0340 code? This code indicates a problem with the camshaft position sensor A circuit. There can be a few components that can trigger this code, so let’s dive right in.

Common causes

Camshaft position sensor

The first cause for the P0340 code is a faulty camshaft position sensor. If the sensor malfunctions, it can either send a weak signal or it might not send one at all. When there’s an incorrect signal, the engine control module detects it and triggers the P0340 code. Also, in rare cases, the camshaft position sensor can get arched, which can throw off the correct spacing needed and set the code.

Here’s the location of the camshaft position sensor A in a 2016 Ford Fusion. It’s typically gonna be on the intake side. If you can't find it in your vehicle, you can refer to this excellent repair manual.

Wiring

The second potential cause is bad wiring. If any wires within the camshaft sensor circuit are damaged or torn, it will prevent the proper signal from being received by the ECM, and in turn, will throw the P0340 code.

Connector

The next possible cause is the camshaft sensor connector. If it’s corroded or damaged, it will disrupt the proper signal, causing the P0340 code. Also, sometimes the connector can just be loose, so make sure it’s secured tightly.

Trigger wheel

The fourth cause for the P0340 code is a bad trigger wheel. The purpose of the trigger wheel is to help the camshaft position sensor measure the position of the camshaft. If the trigger wheel is misaligned or damaged, the camshaft position sensor will send inaccurate data to the ECM, which can trigger the code.

Timing belt/chain

Another possible cause of the P0340 code is a bad timing chain or timing belt. Your car could have either one. The timing belt or chain ensures that the camshaft and crankshaft stay synchronized. If it jumps a tooth on one of the sprockets, it can disrupt the precise timing between the camshaft and crankshaft, leading to the P0340 code.

Alternator

The sixth possible cause is a faulty alternator. Now, this will be more rare than the previous symptoms, but I’ve seen it happen. A faulty alternator can create ripples in the AC voltage that can affect other sensor’s performance.

Engine Control Module

Lastly, your car’s computer can be faulty. If you checked everything that we talked about previously and still couldn't find the issue, you might want to look into the ECM next.