E 212 HCombustion air, gas, overheat, or electronics fault
The Combi may be missing combustion air, fuel, or power, and unresolved cases can indicate an electronics defect.
Plain-English answer
E 212 H has several manufacturer-listed causes: a blocked combustion-air inlet or exhaust, a closed gas valve, defective gas-pressure regulation, activated overheat protection, or faulty electronics.
What to check first
- 01
From outside the RV, inspect the combustion-air inlet and exhaust outlet for snow, mud, nests, or covers.
- 02
Confirm the appliance gas shutoff valve is open.
- 03
Turn the Combi off, let it cool fully, fill the water container with cold water, and clear interior air openings.
Stop and call a technician when
- Do not insert tools into the exhaust or dismantle the gas system.
- If the error remains, Truma notes that electronics or gas regulation may require professional service.
Check the exact manual
Applicability: Truma Combi furnace and water-heater systems. The data plate and specification letter determine which procedure is correct.
Open Truma Combi error-code tech tip ↗Source reviewed August 2026Separate an external blockage from a service-level fault
E212H is a multi-cause code, so replacing parts from the code alone is not a valid diagnosis. Record when it appears and inspect only the external conditions that Truma makes owner-accessible.
Inspect the outside terminal
With the appliance off, look for a storage cover, snow, mud, insect debris, or nesting material at the combustion-air inlet and exhaust. Do not insert tools or remove the terminal.
Allow the appliance to cool
Let the Combi cool completely, confirm the water container is filled with cold water, and make sure interior warm-air outlets and the circulated-air intake are open.
Preserve the fault for service
If the code returns with the external air path and gas shutoff confirmed, stop resetting. Gas-pressure regulation or electronics requires model-specific Truma diagnosis.