Onan Code 36 Fix: Complete Troubleshooting Guide for RV Owners

In Brief

Yesterday your Onan generator was dead silent with that dreaded Code 36 flashing — by tonight it'll be purring back to life and powering your entire RV. Despite having a full propane tank, the issue is likely with the LP regulator, LP gas solenoid valve valve, or a restriction in the gas line preventing adequate fuel pressure from reaching the generator.

Materials List

• Multimeter
• Manometer or fuel pressure gauge
• Basic hand tools (wrenches, screwdrivers)
• Compressed air or shop vacuum
• Soapy water solution for leak detection
• Replacement LP regulator (if needed)

Fixing the Problem

1. Safety first: Turn off the LP tank valve and allow several minutes for gas to dissipate before beginning any diagnostic procedures.
2. Check the LP regulator: The most common cause of code 36 is a faulty LP regulator. Locate the regulator (usually mounted near the generator) and inspect for damage, corrosion, or debris. The regulator should maintain proper pressure for your specific generator model (typically around 11 inches of water column - verify in your service manual).
3. Test LP system pressure: Carefully connect a manometer to the appropriate test port at the generator inlet following proper safety procedures for pressurized LP systems. It should read approximately 11 inches of water column. Lower pressure indicates regulator failure or line restriction.
4. Inspect gas lines: Check all LP gas lines from the tank to the generator for kinks, damage, or obstructions. Pay special attention to the line between the regulator and the generator.
5. Test LP gas solenoid valve operation: Attempt to start the generator and listen for a clicking sound from the LP gas solenoid valve when it attempts to start. If you don't hear clicking, the solenoid may not be receiving power or may be faulty.
6. Verify electrical connections: Using your multimeter, check for 12V DC power at the LP gas solenoid valve connector when the generator is starting. Clean any corroded connections and ensure tight connections.
7. Check for air in lines: If the RV has been sitting for extended periods, air may have entered the LP lines. Try running another LP appliance (stove, water heater) for a few minutes to purge air from the system.
8. Inspect regulator vent: Ensure the regulator vent hole isn't blocked by insects, debris, or ice. A blocked vent can cause pressure regulation issues.

Situations That Need a Professional

Contact a certified RV technician if you encounter any of these situations:

• You're uncomfortable working with LP gas systems
• You detect any propane leaks during testing
• The generator control board shows multiple error codes
• You lack the proper tools for pressure testing
• The issue persists after replacing obvious components

Safety Warning: LP gas work can be dangerous. If you smell propane at any time, immediately shut off the tank valve, evacuate the area, and call a professional.

Stay Ahead of Problems

To prevent future code 36 issues:

• Run your generator monthly for at least 30 minutes under load to prevent fuel system stagnation
• Have your LP system inspected annually by a certified technician
• Keep the generator compartment clean and free of debris that could clog vents or lines
• Consider installing a fuel filter in the LP line to prevent contamination
• When storing your RV, consider shutting off the LP tank valve to prevent slow leaks

Since your generator worked fine on your last trip but failed after propane refilling, focus first on the LP regulator and checking for air in the lines. Many RV owners successfully resolve code 36 issues by replacing the LP regulator, which typically costs $50-100 and can be installed with basic tools.

Tools & Supplies You'll Need

Fix It Right. Fix It Once.

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