What causes a P0427 code?

P0427 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 P0427 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0427 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

P0427

Catalyst Temperature Sensor Low Input Bank 1

What it means

The Engine Control Module (ECM) has detected a low voltage signal from the Catalyst Temperature Sensor, indicating the sensor or circuit is grounded or reporting temperatures below operating thresholds.