What causes a P1875 code?

P1875 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 P1875 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1875 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

P1875

Relative humidity sensor out of range low

What it means

The Engine Control Module (ECM) detects a voltage signal from the relative humidity sensor that is below the minimum calibrated threshold (typically near 0V), indicating an open circuit or short to ground.