The P0340 OBD2 code is often your first sign that there’s a problem with your camshaft position sensor. While this might not sound like a serious issue, malfunctions of this sensor can disrupt the timing of your fuel injectors. This can lead to misfires and even prevent your car from starting.
While there aren’t always drivability issues when the P0340 trouble code activates, you should diagnose and repair the code as quickly as possible to avoid complications. Read on below to learn how to identify the source of the problem and what you need to do to fix it.
P0340 Code Definition
Camshaft Position Sensor Circuit Malfunction
What Does P0340 Mean?
The P0340 OBD2 code tells you a problem has been detected in the camshaft’s position sensor circuit. This sensor is inside the combustion engine and tracks the rotation speed and position of the camshaft. The power control module then uses this data to control the timing of the fuel injectors and spark plugs.
If the timing of the spark plugs or the fuel injectors fails, the P0340 trouble code is triggered. It’s also triggered by any break in the signal between the power control module and the camshaft position sensor. Because of this, the root cause could come from a variety of sources.
What Are The Symptoms Of The P0340 Code?
In some cases, there are no noticeable symptoms that occur with the P0340 code other than the check engine light. The symptoms can also be quite severe, however, and can include:
- Activation of the check engine light
- Difficulty starting or failure to start
- Rough idling and stalling
- Engine misfires
- Reduced engine power
What are the causes of P0340?
Two systems are likely to be the root cause of the P0340 OBD2 code:
- Camshaft position sensor: The sensor itself may be defective or corroded. Damage to the wires around the sensors can also interrupt the signal and trigger the P0340 code.
- Power control module: A fault in the PCM could mean it fails to send the information from the sensor on to the fuel injectors, interrupting the engine’s timing.
How Serious Is The P0340 Code?
P0340 is a very serious code. Issues with the timing of your fuel injectors can lead to misfires, and those can cause serious damage to your engine. You should avoid driving your vehicle until you determine what triggered the P0340 code and repair it as soon as possible, especially if you’re also noticing drivability issues.
How To Diagnose The P0340 Code?
Tools you’ll need:
- Read your system to see if any other codes come up. If you also read codes P0300-P0308, fix those first. Misfiring cylinders could be the root cause of the code.
- Inspect the wiring around the camshaft position sensor. Replace any wires that are damaged or corroded and make sure that they’re all connected securely.
- Determine whether your car has an inductive (1-2 wire) or hall-effect (3-4 wire) camshaft position sensor, then use a digital multimeter to test it.
- If you have an inductive sensor, unplug the connection and set the multimeter to DC voltage at a low range. Turn your ignition on without starting the engine. Connect the black lead to the negative post on your battery and the red lead to the wires on the sensor harness. If none of the wires produces 1.5 volts, the sensor is defective.
- If you have a hall-effect camshaft sensor, remove the fuel pump fuse to prevent the engine from starting, then unplug the connection to the sensor. Set the multimeter to DC voltage with a range of 20 volts. Connect the black lead to the black wire on the sensor harness and the red lead to the red wire on the harness. Turn your ignition on. The multimeter should read between 5 and 13 volts. Turn off the ignition and connect the black lead of the multimeter to the negative post on your battery then have an assistant crank the engine. Touch the red lead to the black ground wire; the multimeter should read 200-300mv. Now touch the lead to the green wire on the harness. The multimeter should read 300mv.
Common Mistakes To Avoid While Diagnosing The P0340 Code
If you determine a faulty camshaft position sensor is to blame for the trouble code, check the wiring around the sensor before you replace it. Faulty wires can interrupt the signal and cause the sensor to read as faulty.
What Should You Do To Fix The Code P0340?
- Repair any misfiring problems indicated by the occurrence of OBD2 codes P0300-P0308.
- Replace any damaged or corroded wires found around the camshaft position sensor. Clear codes and read your car again to see if the code re-appears.
- Remove your camshaft position sensor if it fails the diagnostic test in step 3 above. Inspect the sensor for damage, especially for corrosion around the connectors. Clean the corrosion if you’re able. If you can’t clean the sensor, or if this fails to clear the code, replace the sensor.
- Clear the codes after you’ve replaced the camshaft position sensor. If P0340 comes back, you likely have a problem with your power control module and should take your car to a mechanic.
Tips To Avoid P0340 In The Future
Many mechanics recommend periodically replacing your camshaft position sensor, even if it hasn’t failed, as part of your regular preventative maintenance. While they’re designed to last the full life of the vehicle, if the sensor is over 5 years old you should have it checked by a mechanic whenever you take your car in for an oil change.
Heat from the engine is the main thing that damages your engine’s electronic components. If you regularly push your engine hard for long periods of time, or if you’ve had issues with your engine overheating, you are more likely to have issues with the camshaft position sensor.