What causes a P2249 code?

P2249 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 P2249 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2249 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

P2249

P2249 O2 Sensor Reference Voltage Circuit Low

What it means

This fault indicates that the engine control module (ECM) has detected a voltage signal lower than the calibrated threshold on the O2 sensor's reference voltage circuit, specifically for Bank 1 Sensor 1.