What causes a P156C code?

P156C can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a P156C code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P156C active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

OBD-II

P156C

Coolant Pump 2 PWM driver short circuit high

What it means

The P156C code indicates that the ECM has detected a high voltage state (short to B+) on the Pulse Width Modulation (PWM) control circuit for the secondary/auxiliary coolant pump.