What causes a P156B code?

P156B 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 P156B code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P156B 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

P156B

Coolant Pump 2 PWM driver short circuit low

What it means

The P156B code indicates that the ECM has detected an electrical short to ground on the Pulse Width Modulation (PWM) control circuit for the secondary (auxiliary) coolant pump.