What causes a SPN 422 code?

SPN 422 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 SPN 422 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 422 active.

How do I fix SPN 422?

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

J1939 SPN

SPN 422

J1939 SPN 422 — Fuel/Air parameter

What it means

Engine Coolant Level - Data Erratic, Intermittent, or Incorrect. This is a common J1939 parameter used to monitor the presence of coolant via an electrical signal.