What causes a SPN 877 code?

SPN 877 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 877 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 877 active.

How do I fix SPN 877?

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 877

J1939 SPN 877 — Engine Management parameter

What it means

Ambient Air Temperature sensor signal out of range or data erratic. This sensor is used by the ECM to calculate engine fueling, timing, and cold-start strategies.