Fault 31

Onan Generator: “Fault 31”

danger RV generator fault codes

Safety An over-speeding engine can fail violently. Keep clear and do not run it. This is a fuel-burning engine - if you smell gas or propane, stop and ventilate; never run in an enclosed space due to carbon monoxide.

What it means

Overspeed fault. The engine speed exceeded 3400 rpm, so the controller shut the generator down to protect it. Read as three blinks, a pause, then one blink.

Most likely causes

Governor or governor-actuator malfunction allowing engine to run away common
Controller / speed-sensing fault common
Throttle/linkage or fuel system fault driving speed too high less common

Safe checks you can do yourself

Note the conditions when it tripped, but do not attempt to defeat or readjust the governor yourself.
Confirm the code by reading the blink pattern (3 then 1) to be sure it is overspeed (31) and not engine-stopped (36).

How to reset / clear Fault 31

The official corrective action is to see an authorized Onan dealer - overspeed is not a homeowner adjustment.
To re-read the logged code, press Stop three times within 5 seconds (the code stops blinking after about 5 minutes).

When to call a technician

Always for overspeed - the manufacturer directs you to an authorized Onan/Cummins dealer rather than DIY repair.

Applies to

Onan RV QG / KY series RV gensets · Onan blink-code-controller RV gensets (HGJAA/HGJAB-class)

FAQ

What does Onan Generator code "Fault 31" mean?

Overspeed fault. The engine speed exceeded 3400 rpm, so the controller shut the generator down to protect it. Read as three blinks, a pause, then one blink.

How do I reset Onan Generator Fault 31?

The official corrective action is to see an authorized Onan dealer - overspeed is not a homeowner adjustment. To re-read the logged code, press Stop three times within 5 seconds (the code stops blinking after about 5 minutes).

What is the most common cause of Fault 31 on a Onan Generator?

The most likely cause is governor or governor-actuator malfunction allowing engine to run away.

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Sources

Onan RV Generator Troubleshooting Codes (Table 5) — TABLE 5 - OVERSPEED FAULT-CODE NO. 31 (Engine speed greater than 3400 rpm) (Cummins/Onan (hosted by Heartland Owners))

Note: Code 31 is the true overspeed code; it is frequently confused with code 36.

● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.