What causes a SPN 28 code?

SPN 28 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 28 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 28 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

J1939 SPN

SPN 28

J1939 SPN 28 — Engine parameter

What it means

SPN 28 typically refers to an Accelerator Pedal Position #3 signal. This indicates the ECM is receiving an out-of-range or inconsistent voltage from the third redundant sensor in the accelerator pedal assembly.