What causes a P127A code?

P127A 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 P127A code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P127A 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

P127A

EGR mass flow sensor egr too low fault data

What it means

Exhaust Gas Recirculation (EGR) Mass Flow Sensor indicates that the actual EGR flow is significantly lower than the commanded or expected flow rate.