What causes a P0428 code?

P0428 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 P0428 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0428 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

P0428

Catalyst Temperature Sensor High Input (Bank 1 Sensor 1)

What it means

The Engine Control Module (ECM) has detected a voltage signal from the inlet DOC or SCR temperature sensor that exceeds the calibrated maximum limit, typically indicating an open circuit or short to power.