What causes a P203D code?

P203D 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 P203D code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P203D 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

Log in Sign up

OBD-II

P203D

Reductant Level Sensor Circuit High

What it means

Signal voltage from the DEF level sensor is higher than expected, indicating an open circuit.

Sign in to view symptoms, probable causes, diagnostic steps, severity, and related codes

Log in Sign up free