Onan Generator: “Fault 36”
warning RV generator fault codes
What it means
Engine Stopped fault. The engine stopped on its own without the controller commanding a shutdown. Despite being one of the most-searched Onan codes, code 36 is NOT overspeed (that is code 31) - it most often means the genset simply ran out of fuel, lost spark, or stalled from a fuel/air problem. Read as three blinks, a pause, then six blinks.
Most likely causes
- Out of fuel - on shared tanks the generator pickup tube sits higher than the vehicle engine pickup, so the genset runs dry first (often around 1/4 tank) most likely
- LPG supply too low or, on cold days, insufficient vaporization rate to meet demand common
- Weak or fouled spark - loose spark-plug leads or worn spark plugs common
- Clogged air cleaner restricting airflow less common
- Mechanical damage or other engine fault rare
Safe checks you can do yourself
- Check the fuel gauge and refill; never run a shared tank below about 1/4 for the generator. Mark the genset 'empty' point on the gauge.
- On LPG units, confirm the tank is adequately full (keep it at least half full in cold weather).
- Visually confirm spark-plug wires are seated and the air cleaner is not clogged (with engine off and cool).
- Make sure all fuel valves are open.
How to reset / clear Fault 36
- Correct the underlying cause (usually refuel) first.
- On gasoline models, prime the fuel system by holding the control switch at Stop/Prime for about 30 seconds, then attempt a restart.
- Wait about 5 seconds for the controller to reset between start attempts.
- Note: the controller logs the last fault and will keep blinking it for ~5 minutes (15 minutes on HGJAA series); pressing Stop three times within 5 seconds restores the blink display. The logged code clears on the next successful run/start cycle.
When to call a technician
Fuel and spark are confirmed good but the genset still stops on code 36, or you suspect mechanical damage. Internal repairs should go to an authorized Onan/Cummins dealer.
Applies to
Onan RV QG / KY series RV gensets (e.g. KY Spec J-N) · Onan Marquis / Microlite / Emerald style RV gensets using the blink-code controller · HGJAA / HGJAB-class units (note longer 15-minute blink retention on HGJAA)
FAQ
What does Onan Generator code "Fault 36" mean?
Engine Stopped fault. The engine stopped on its own without the controller commanding a shutdown. Despite being one of the most-searched Onan codes, code 36 is NOT overspeed (that is code 31) - it most often means the genset simply ran out of fuel, lost spark, or stalled from a fuel/air problem. Read as three blinks, a pause, then six blinks.
How do I reset Onan Generator Fault 36?
Correct the underlying cause (usually refuel) first. On gasoline models, prime the fuel system by holding the control switch at Stop/Prime for about 30 seconds, then attempt a restart. Wait about 5 seconds for the controller to reset between start attempts. Note: the controller logs the last fault and will keep blinking it for ~5 minutes (15 minutes on HGJAA series); pressing Stop three times within 5 seconds restores the blink display. The logged code clears on the next successful run/start cycle.
What is the most common cause of Fault 36 on a Onan Generator?
The most likely cause is out of fuel - on shared tanks the generator pickup tube sits higher than the vehicle engine pickup, so the genset runs dry first (often around 1/4 tank).
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Sources
- Onan RV Generator Troubleshooting Codes (Table 5) — TABLE 5. TROUBLESHOOTING - ENGINE STOPPED FAULT-CODE NO. 36 (Cummins/Onan (hosted by Heartland Owners))
- Operator Manual RV Generator Set KY (Spec J-N), 0981-0159 — Troubleshooting section, Fault Codes / Table 2 (Fault Code No. 36 blink example) (Cummins Inc.)
Note: Common misconception: many forum posts call code 36 'overspeed' or 'overheat'. The official Onan table defines 36 as 'Engine Stopped' (overspeed is code 31). The frequent real-world cause is fuel starvation.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.