Cummins Onan · HGLAA PMA-equipped generator sets
Code 25Alternator over voltage
Permanent-magnet alternator output voltage was above its permitted range.
What it means
Plain-English answer
The controller detected high PMA voltage and shut the generator down. Diagnosis involves internal generation and sensing circuits.
Owner-safe checks
What to check first
- 01
Turn the generator off and remove connected loads.
- 02
Record the exact model and fault-code sequence.
- 03
Keep the cooling-air openings clear while awaiting service.
Safety boundary
Stop and call a technician when
- Do not open the generator to measure PMA voltage.
- Contact a Cummins dealer or qualified generator technician.
Primary reference
Check the exact manual
Applicability: HGLAA PMA-equipped generator sets. The data plate and specification letter determine which procedure is correct.
Open Cummins Onan operator manual ↗Source reviewed August 2026