What causes a P1868 code?

P1868 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 P1868 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1868 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

P1868

Ambient air temperature sensor out of range high

What it means

The Ambient Air Temperature (AAT) sensor signal voltage is higher than the maximum calibrated threshold (typically indicating a short-to-ground or low resistance fault in the circuit).