P20C4

DTC P20C4, sometimes indicated as P20C400 is an OBD diagnostic trouble code indicating a manufacturer-specific fault with the vehicle powertrain (i.e. engine and gearbox). This code identifies an error with the air/fuel mixture causing reductant heater "c" control circuit high.

The reductant heater "C" control circuit high fault code is caused when the reductant heater "C" control circuit is high. This fault code can be caused by a number of things, including a failed reductant heater "C" control circuit, a failed reductant heater "C" relay, or a failed reductant heater "C" fuse.
The first step in troubleshooting this fault code is to check the reductant heater "C" control circuit for continuity. If the control circuit is open, then the fault is most likely a failed reductant heater "C" control circuit. If the control circuit is closed, then the fault is most likely a failed reductant heater "C" relay or a failed reductant heater "C" fuse.
If the fault is a failed reductant heater "C" control circuit, then the reductant heater "C" control circuit should be replaced. If the fault is a failed reductant heater "C" relay or a failed reductant heater "C" fuse, then the appropriate relay or fuse should be replaced.

• P20C4: Reductant Heater C Control Circuit High
• P20C4: Reductant Heater "C" Control Circuit High
• P20C4: Reductant heater control C – circuit high
• P20C4 00: Reductant heater control C - circuit high