What causes a P1134 code?

P1134 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 P1134 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1134 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

P1134

WRAF heater CJ125 short-circuit to ground fault for heater diagnostic

What it means

Detailed electrical fault indicating the Wide-Range Air-Fuel (WRAF) sensor heater circuit, controlled by the CJ125 interface, has shorted to ground, preventing the sensor from reaching its required operating temperature.