What causes a P0637 code?

P0637 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 P0637 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0637 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

P0637

Power Steering Control Circuit High Malfunction

What it means

The Engine Control Module (ECM) has detected an abnormally high voltage signal in the power steering pressure switch or control circuit. This signal indicates the electrical resistance is outside of the expected operating parameters for the power steering system monitoring.