What causes a P2478 code?

P2478 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 P2478 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2478 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

P2478

Exhaust Gas Temperature Bank 1 Sensor 2 Out of Range

What it means

The Engine Control Module (ECM) has detected that the temperature reading from the Diesel Oxidation Catalyst (DOC) outlet/DPF inlet sensor is outside of calibrated limits.