What causes a P2240 code?

P2240 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 P2240 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2240 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

P2240

P2240 O2 Sensor Positive Current Control Circuit Open Bank 1 Sensor 1

What it means

The Engine Control Module (ECM) detects an open circuit in the positive current control branch of the upstream oxygen sensor (O2), preventing accurate monitoring of exhaust gas air-fuel ratios.