Propane safety: Stop immediately if you smell propane, see soot, hear delayed ignition, see flame roll-out, or find melted wiring. Gas appliances should be serviced by qualified propane technicians.

Most modern RV water heaters use direct spark ignition for propane mode. When you turn the switch on, the board needs 12V power, then it opens the gas valve and sparks. If flame is not proven, the board locks out.

1. Confirm the tank is full before heating

Do not run any water heater empty. Open a hot faucet until water flows steadily with no air bursts. If the heater was winterized, confirm the bypass valves are returned to normal before attempting propane or electric heating.

2. Verify propane supply

Light a stove burner and watch for a steady blue flame, then turn it off. If the propane cylinder was recently changed, air may still be in the line. Try one normal water-heater reset after supply is confirmed. Do not keep cycling if odor develops.

3. Check 12V controls

The propane burner still depends on 12V DC for the switch, control board, gas valve and igniter. Check the RV fuse panel and measure voltage if you are comfortable with safe DC testing. A weak battery or poor ground can make the heater act like a propane problem when the real issue is control power.

4. Listen for the ignition attempt

  • No click: switch, fuse, board, thermostat, limit circuit or wiring may be stopping the sequence.
  • Clicking but no ignition: propane supply, burner obstruction, electrode, gas valve or gas pressure may be involved.
  • Lights then shuts off: flame sensing, grounding, electrode position or unstable combustion may be the issue.

5. Inspect the exterior compartment

With the heater off and cool, open the outside access door. Look for insects, nests, loose visible wires, water intrusion or obvious soot. Do not push tools into the burner tube or gas orifice. Do not adjust air shutters unless the manual and training support it.

6. Check for lockout and reset properly

Many heaters turn on a fault light after failed ignition. Turn the water-heater switch off, wait as directed by the manual, then try one reset after basic supply checks. Repeated lockout is information. It is not an invitation to keep trying until something ignites late.

Related water-heater pages

FAQ

Why does the fault light come on?

The control did not prove normal operation, often because flame was not established or sensed. Use the manual for your exact model's fault behavior.

Can low propane pressure affect only the water heater?

Yes. Different appliances have different burner demands and ignition sensitivity. Weak pressure can show up first on one appliance.

What if the water heater works on electric?

That confirms the tank can heat water, but it does not prove the propane burner, gas valve, electrode or flame-sense circuit is working.

Follow the water-heater path

The appliance troubleshooter separates bypass, electric, propane and lukewarm symptoms.

Diagnose water heater

Sources and review notes

Follow the installed water-heater manual and the RV manufacturer's wiring/plumbing diagrams. Suburban RV service support notes that Suburban gas appliances should be installed and serviced by certified gas technicians or authorized service centers.