What causes a P1226 code?

P1226 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 P1226 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1226 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

P1226

Cylinder 1 2 or 3: Injector needle valve high side short circuit to battery voltage

What it means

The ECM has detected battery voltage on the high-side supply circuit for fuel injectors 1, 2, or 3 when it was not commanded. This usually indicates a short circuit.