Cummins Onan · HGLAA and compatible PMA-equipped generator sets

Code 27PMA sense lost

The controller did not detect the expected permanent-magnet alternator signal and shut the generator down.

Published by RV Fault Finder · Independent referencePrimary source checked August 2026How this guide is researched →

What it means

Plain-English answer

This is a generator sensing fault, not a routine maintenance reminder. The manufacturer directs owners to qualified service because diagnosis involves internal electrical measurements.

Owner-safe checks

What to check first

01
Leave the generator off and disconnect RV loads.
02
Record the full model and specification from the data plate.
03
Inspect only the exterior ventilation area for obvious obstruction or debris.

Safety boundary

Stop and call a technician when

Do not open the generator or test PMA wiring unless you are trained for generator service.
Contact a Cummins dealer or qualified generator technician.

Primary reference

Check the exact manual

Applicability: HGLAA and compatible PMA-equipped generator sets. The data plate and specification letter determine which procedure is correct.

Open Cummins Onan operator manual ↗Source reviewed August 2026