Technical Description of OBD-II Trouble Code
Misfire in a Single Cylinder (Cylinder not Specified)
What does that signify?
This generic powertrain/engine diagnostic trouble code is applicable to most manufacturers since 1996.
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), the camshaft position sensor (CMP), and the engine controller (ECM/PCM). The PCM monitors the relationship between these two sensors and compares them to an ideal reference stored in the PCM. If the variation exceeds a calibrated percentage, a fault code is stored. This can be either 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:
Causes
Typically, the causes for this code to set are:
Most Common Issues:
Least likely:
Diagnostic Steps and Repair Information
A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known issue with a known fix provided by the manufacturer and can save you time and money during diagnosis.
Next, note if there are any other diagnostic fault codes. If any of them are ignition system/fuel system related, diagnose them first. Misdiagnosis has been known to occur if a technician diagnoses this code before thoroughly diagnosing and dismissing any ignition system / fuel system related codes. Ensure there are no intake or exhaust leaks. An intake leak, or vacuum leak, causes the engine to run lean. An exhaust leak gives the impression of a lean running engine according to the air/fuel ratio sensor/oxygen sensor (AFR/O2).
After that, clear all diagnostic trouble codes and see if the P0314 returns. If it does not, then the problem was intermittent or the P0314 was a memory code, indicating that it was something in the past.
If the code resets, that is, it comes right back the next time you start the vehicle or during the next road test, further inspection is required. Locate the CKP sensor and the CMP sensor on your particular vehicle. Once located, visually inspect the connectors and wiring. Look for scraping, rubbing, bare wires, burned spots, or melted plastic. Pull the connectors apart and carefully inspect the terminals (the metal parts) inside the plastic connectors. Check if they appear burnt or corroded instead of the normal metal color. If cleaning the terminals is necessary, use electrical contact cleaner and a plastic bristle brush. If not available, rubbing alcohol and a toothbrush can be used, but ensure the toothbrush is not returned to the bathroom afterwards! After cleaning, let the terminals air dry and apply some dielectric silicone compound (the same stuff used for light bulb sockets) where the terminals come into contact.
Clear the diagnostic trouble codes from memory again and see if this code returns. If it does not, then the connections were most likely the problem.
If the code does return, remove the CKP sensor and the CMP sensor from the engine. Examine the end of the sensor where it comes close to the timing components / flex plate / flywheel on the engine. Check for any damage, indicating that it may have been struck by any of those components. If there is damage, the sensor will need to be replaced. It is recommended to replace it with one from the OEM or dealer, as aftermarket sensors may not meet the voltage specifications that the PCM requires. With this code, which relates 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 could cause the engine to lose its ability to identify individual cylinders.
If the previous tests have passed and the code is still present, monitor the air/fuel ratio sensor/oxygen sensor (AFR/O2). If it consistently indicates that the engine is running lean, investigate all possibilities that could cause a lean running/misfiring engine. These include:
Once again, it is crucial to diagnose all other codes before addressing this one, as issues that cause other codes to set can also cause this one to set.
If the code still cannot be cleared, the only remaining option is to seek assistance from a trained automotive drivability diagnostician.
