P0340: Camshaft Position Sensor Circuit Malfunction

What is P0340?

Error code P0340 is an OBD-II diagnostic trouble code defined as “Camshaft Position Sensor Circuit Malfunction.” 

It refers to the entire circuit attached to the camshaft position sensor. This could be vehicle parts like the electric wiring in and around your camshaft position sensor (CMP sensor or cam sensor), the CMP sensor itself, as well as your Engine Control Module (ECM) and Powertrain Control Module (PCM). 

As such, just replacing the camshaft position sensor is often not enough to fix the P0340 fault code.

Your CMP sensor calculates your engine’s camshaft rotation speed and keeps track of the shaft’s exact position during rotation. It also signals to the PCM or ECM to set the fuel injector timing and, in conjunction with the crankshaft position sensor (crank sensor) to set the ignition timing.

Any disruption to the signal throws off the engine timing and can lead to the P0340 trouble code being set.

Common symptoms

You may experience one or more of these common symptoms with an active P0340 fault code:

• Illuminated check engine light
• Engine cranking without starting
• Engine stalling
• Engine misfires or rough running
• Loss of power while driving
• Transmission shifting issues
• Increased fuel consumption
• No spark when you turn the ignition switch

Can I still drive?

Immediately discontinue driving if you have an active P0340 code.

DTC P0340 is a severe error code, and it could be dangerous to continue driving with this fault code. You don’t want to risk your engine stalling while you’re driving on the highway.

Furthermore, you risk damaging your vehicle’s ignition system if you continue to drive with this fault code active — leading to an expensive repair job.

P0340 causes

Here are the most common causes of DTC P0340:

• A faulty camshaft position sensor won’t accurately signal to your PCM when to inject fuel.
• An open circuit within the camshaft position sensor circuit wiring means the communication between your engine computers and the camshaft sensor is compromised.
• A defective connector to your camshaft position sensor circuit interferes with the signal between the sensor and your engine computers.
• A faulty crankshaft position sensor means your PCM or ECM won’t know when to set the ignition timing.
• A faulty crankshaft position sensor reluctor wheel means your ECM or PCM won’t accurately track your crankshaft’s position.
• A defective PCM or ECM won’t accurately pick up the signals from your cam sensor or crank sensor.

Diagnosis

Here’s how your mechanic will diagnose error code P0340 to find the root cause of the problem:

• First, your mechanic will use a scan tool to retrieve all other trouble codes stored by your PCM or ECM.
• Next, they’ll check the continuity of the cam position sensor circuitry by inspecting the cam sensor wiring and wiring harness. They’ll check to see if there’s been a short circuit or if any CMP sensor wiring is frayed.
• Then, they’ll check each camshaft position sensor connector (harness connector) to see if they’re broken or corroded.
• Your mechanic will use a scan tool to test your camshaft sensor voltage reading.
• They’ll then look at your crankshaft position sensor and crank sensor circuit wiring to see if there’s any damage.
• They’ll inspect your timing belt for any faults.
• Finally, they’ll inspect your Powertrain Control Module or Engine Control Module to see if they’re defective or damaged.

Possible repairs for P0340 & Costs

Since there are multiple possible causes of Check Engine Light code P0340, your mechanic will need to complete the entire diagnostic process before performing any repairs. 

You don’t want to pay for a new Powertrain Control Module or Engine Control Module when your CMP sensor wiring is causing a short circuit problem.

Here’s how a mechanic will fix the different causes of error code P0340:

• Other error codes: Your mechanic will fix any other active error codes you may have in order of seriousness.
• Camshaft position sensor: Your mechanic will replace your cam position sensor wiring and each camshaft position sensor connector if they’re damaged, corroded, or frayed. Then, they’ll replace your faulty camshaft position sensor if it’s required.
• Crankshaft position sensor: They’ll perform the same repairs on your crank sensor. So, your mechanic will replace your crankshaft position sensor wiring and each harness connector if they’re damaged. They’ll also give you a new crankshaft position sensor if yours is faulty.
• Timing belt: If your timing belt slips, it’s very difficult for your mechanic to put it back in position. So, your mechanic will likely replace it with a new one. Your timing belt should be replaced every 60,000-100,000 miles.
• PCM & ECM: If none of the above repairs resolve the issue, your mechanic will try fixing your PCM and ECM. If they’re damaged beyond repair, they’ll install new ones for you.

Here’s an estimate of how much some different repair jobs will cost when fixing the P0340 code:

• Replace camshaft sensor: $120-$300
• New crankshaft position sensor: $190-$250
• Timing belt replacement: $200-$1000
• ECM replacement: $1000-$1200
• New PCM: $800-$1500

Note: The repair costs mentioned above include labor charges.