What causes a P1841 code?

P1841 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 P1841 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1841 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

P1841

Upstream NOx sensor AT1IGC2 high rate fault

What it means

The Upstream NOx sensor is reporting a NOx concentration level that exceeds the expected range or is changing at a rate that is physically impossible under current engine operating conditions.