What causes a P1490 code?

P1490 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 P1490 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1490 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

P1490

EGR valve stuck open

What it means

The Engine Control Module (ECM) has detected that the Exhaust Gas Recirculation (EGR) valve is not reaching its commanded closed position, resulting in excessive exhaust gases entering the intake manifold at idle or under load.