What causes a P1839 code?

P1839 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 P1839 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1839 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

P1839

Upstream NOx sensor AT1IGC1 high rate fault

What it means

The Engine Control Module (ECM) detects that the Upstream NOx sensor is reporting values that are changing at an implausible rate (signal noise) or are stuck outside of normal operating parameters.