What causes a P2078 code?

P2078 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 P2078 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2078 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

P2078

Intake Manifold Tuning Valve Position Sensor High Circuit

What it means

The Engine Control Module (ECM) detects a high voltage signal from the Intake Manifold Tuning Valve (IMTV) position sensor, indicating a signal out of specified range.