OBD-II Trouble Code Technical Description
The glow plug in Cylinder 1 is incorrect.
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that is typically found in OBD-II vehicles, including VW, Audi, Ford, GMC, Ram, Chevy, etc. However, it is most commonly seen in Volkswagen / VW vehicles. The exact repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
When the code P06C5 is stored, it indicates that the powertrain control module (PCM) has detected an incorrect level of resistance in the glow plug circuit for cylinder #1. To determine the location of the #1 cylinder for your specific vehicle, consult a reliable source of vehicle information.
In diesel engines, glow plugs are used to increase cylinder temperature and maximize compression, as there is no spark involved. Each cylinder has a glow plug threaded into the cylinder head, and when voltage is correctly applied, the glow plug will glow red hot and aid in increasing cylinder temperature. Once the desired temperature is reached, voltage is restricted and the glow plug returns to its normal state.
If the PCM detects an unexpected resistance with the cylinder #1 glow plug, it will store the code P06C5 and may illuminate the malfunction indicator lamp (MIL).
Photo of a typical glow plug:
What is the severity of this DTC?
Any code related to glow plugs is likely to cause drivability issues. It is important to address a stored code P06C5 with urgency.
What are some of the symptoms of the code?
Symptoms of a P06C5 trouble code may include:
What are some of the common causes of the code?
Possible causes for this P06C5 fuel injector code may include:
What are some P06C5 troubleshooting steps?
In order to accurately diagnose a code P06C5, you will need a diagnostic scanner, a reliable source of vehicle information, and a digital volt/ohmmeter (DVOM). Use the vehicle information source to search for applicable technical service bulletins (TSB) that match the vehicle make, model, symptoms, and stored code. This information will help in the diagnosis process.
After visually inspecting all glow plugs and glow plug control wiring and connectors, connect the diagnostic scanner to the vehicle diagnostic port. Retrieve all stored codes and freeze frame data, and record them for reference. Test drive the vehicle to see if the code P06C5 is reset. If it is reset, continue with the diagnosis. If not, you may be dealing with an intermittent condition that requires further worsening for an accurate diagnosis.
Be cautious when performing tests to avoid burns or fires. To test glow plugs, you can remove them and apply battery voltage. If the glow plug glows bright red, it is functioning properly. If it fails to heat up, it is defective. For the stored code P06C5, it is recommended to test it with a DVOM to check if it complies with the manufacturer’s resistance specifications.
If the glow plugs appear to be working properly, use the scanner to activate the glow plug timer and test for battery voltage (and a ground) at the glow plug connector using the DVOM. If no voltage is present, test the power supply for the glow plug timer or glow plug controller. Test all related fuses and relays as recommended by the manufacturer. It is important to test system fuses and fusible links with the circuit loaded to avoid diagnostic errors.
If all fuses and relays appear to be functional, use the DVOM to test the output voltage at the glow plug timer or PCM. If voltage is detected at the glow plug timer or PCM, there may be an open or shorted circuit. You can investigate the cause of the discrepancy or simply replace the circuit.
