What causes a P0669 code?

P0669 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 P0669 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0669 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

P0669

PCM/ECM/TCM Internal Temperature Sensor High Circuit

What it means

The Engine Control Module detects a voltage signal from its internal temperature sensor that is above the maximum calibrated threshold. This indicates that the control module processor is overheating or the internal monitoring circuit has failed.