What causes a P1135 code?

P1135 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 P1135 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1135 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

P1135

WRAF heater CJ125 short-to-battery fault

What it means

This code indicates that the heater control circuit for the Wide-Range Air-Fuel (WRAF) sensor has detected voltage higher than expected, suggesting a short to a voltage source (short to battery). This prevents the sensor from reaching its operating temperature.