What causes a P0479 code?

P0479 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 P0479 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0479 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

P0479

Exhaust Pressure Control Valve Circuit Intermittent

What it means

The Engine Control Module (ECM) detects an intermittent or erratic voltage signal from the exhaust back pressure sensor or control valve circuit. This fault disrupts the precise regulation of exhaust pressure needed for turbocharger performance and emissions control.