What causes a SPN 987 code?

SPN 987 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 987 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 987 active.

How do I fix SPN 987?

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 987

J1939 SPN 987 — Engine Management parameter

What it means

SPN 987 typically refers to the Engine Retarder Selection or Retarder Enable signal. It indicates a fault in the circuit that informs the ECM of the driver's request to engage or toggle engine braking levels.