What does it mean?
This generic powertrain/drivetrain diagnostic trouble code generally applies to most manufacturers from 1996 onwards.
These manufacturers include, but are not limited to, GM, Ford, Dodge, Chrysler, Jeep, Hyundai, Kia, Mazda, Mitsubishi, Volvo, and VW.
This code focuses on the relationship between the crankshaft position sensor (CKP), camshaft position sensor (CMP), and the engine control module (ECM/PCM). The PCM monitors the relationship between these two sensors and compares it to an ideal reference stored in the PCM. If the variation exceeds a calibrated percentage, a trouble code is stored. It could be an electrical fault or a mechanical issue, depending on the reason for the misfire and the vehicle manufacturer.
Troubleshooting steps may vary depending on the manufacturer and the type of crankshaft position sensor (CKP), camshaft position sensor (CMP), and their wire colors.
Symptoms
Symptoms of a P0314 engine code may include:
Malfunction Indicator Lamp (MIL) illuminated
Misfires/rough running or surging
Lower than normal fuel economy
Causes
Typically, the causes for this code to set are as follows:
Most common issues:
Worn ignition system components, including the coil, spark plug wires, spark plugs, etc.
Fuel system components – to include injectors
Less likely:
Intermittent open in the power, ground, or signal circuit to the crankshaft position sensor
Intermittent open in the power, ground, or signal circuit to the camshaft position sensor
Failed PCM – rarely
Diagnostic Steps and Repair Information
A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix published by the manufacturer and can save you time and money during diagnosis.
Next, note if there are any other diagnostic trouble codes. If any are related to the ignition system/fuel system, diagnose them first. Misdiagnosis is known to occur if a technician diagnoses this code before any ignition system/fuel system related codes have been thoroughly diagnosed and dismissed. Ensure there are no intake or exhaust leaks. An intake leak, or vacuum leak, causes the engine to idle roughly. An exhaust leak gives the impression of a lean running engine to the air/fuel ratio sensor/oxygen sensor (AFR/O2).
After that, clear all diagnostic codes and see if the P0314 returns. If not, the problem was intermittent or the P0314 was a memory code, meaning it was something from the past.
If the code resets, meaning it comes back immediately the next time you start the vehicle or on the very next road test, further inspection is needed. Locate the CKP sensor and CMP sensor on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for scrapes, chafing, exposed wires, burnt spots, or melted plastic. Disconnect the connectors and carefully inspect the terminals (the metal parts) inside the plastic connectors. See if they look burnt or corroded instead of the normal metallic color you are probably used to seeing. You can get electrical contact cleaner and a plastic bristle brush at any auto parts store if you need to clean the terminals. If not, find some rubbing alcohol and a toothbrush to clean them, make sure not to put the toothbrush back in the bathroom! Then let them air dry, get some dielectric silicone compound (same stuff they use for light bulb sockets) and put some on where the terminals make contact.
Clear the diagnostic codes from memory again and see if this code returns. If not, the connections were likely your problem.
If the code returns, remove the CKP sensor and CMP sensor from the engine. Look at the end of the sensor where it comes close to the timing components/flexplate/flywheel on the engine. Note if there is any damage, where it might have been hit by any of these components. If it appears to have been hit/damaged, it will need to be replaced. At this point, it is wise to replace it with an original equipment manufacturer part or a dealer part. Repeatedly, technicians have replaced a faulty CKP sensor, only to find they have to replace it again because the aftermarket sensor did not meet the voltage specifications the PCM was looking for. With this code, relating to these two sensors, be more suspicious of the CMP sensor, as the CKP sensor would tend to cause the engine to stall. The CMP sensor might cause it to lose its ability to identify individual cylinders.
If the previous tests passed and the code is still present, monitor the air/fuel ratio sensor/oxygen sensor (AFR/O2). If it continuously indicates the engine is running lean, locate all possibilities that could cause a lean running/misfiring engine. These include:
Intake or exhaust leaks
Fuel system, including fuel pressure regulator/fuel pressure
Fuel pressure sensor
Fuel injectors
Ignition system
Post-catalytic converter O2 sensor
EVAP system, to include the canister purge control valve.
Again, it cannot be overemphasized that all other codes should be diagnosed before this one, as issues causing other codes to set can also cause this one.
If the code still cannot be cleared, the only thing left to do is to seek the assistance of a driveability specialist diagnostician.