Allison WTEC II Fault Code: 65 PID: SPN: 00 FMI: Engine rating too high

Posted by PerDiezel Solutions on January 10, 2026

Main code 65 indicates the engine horsepower/governor speed rating is too high. This code is set only when computer-controlled engines are used. Code 65 means the engine computer is able to tell the transmission, the engine horsepower and/or governor speed is beyond the transmission rating or does not match the transmission shift calibration.

When a code 65 is set, no shifts out of neutral are allowed. It is possible the transmission calibration selected for this engine is improper. Contact local Allison Transmission Division distributor for assistance in selecting a proper calibration.

If the engine is beyond transmission ratings, contact the vehicle OEM for correction. The local ATD regional representative may also be contacted for assistance.

This code cannot be cleared until the proper level engine is installed or the transmission is properly calibrated.

Allison WTEC II Fault Code: 64 PID: SPN: 23 FMI: Retarder modulation request sensor, failed high

Allison WTEC II Fault Code: 64 PID: SPN: 12 FMI: Retarder modulation request sensor, failed low

Allison WTEC II Fault Code: 63 PID: SPN: 41 FMI: Pump/pack and a neutral general purpose input

Allison WTEC II Fault Code: 63 PID: SPN: 40 FMI: Service brake status input failed on

Allison WTEC II Fault Code: 63 PID: SPN: 26 FMI: Kickdown input failed on

Allison WTEC II Fault Code: 63 PID: SPN: 00 FMI: Input function fault

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