RV OWNER’S FIELD GUIDE · APPLIANCES
Truma Combi Troubleshooting
Combines space heating and water heating in one unit — increasingly common in van builds, and not well documented outside Europe. Here’s what to check.
Unit Won’t Ignite
Check 12V supply voltage at the unit first — the Combi’s control board is sensitive to low voltage and will fault out well before the battery is actually “dead.” After that, check LP supply pressure and that the exhaust/intake vent isn’t obstructed — the unit’s airflow sensor will block ignition if it detects restricted venting.
Heats Water but Not Air, or Vice Versa
The Combi runs both functions off one burner but controls them independently through the digital control panel — check that both zones are actually switched on in the panel settings before assuming a hardware fault. A frozen or airlocked water circuit can also prevent water heating while space heat continues working normally.
Error Codes on the Digital Panel
The Combi’s control panel displays a numeric fault code rather than a description. Note the exact code before resetting power — it’s the single most useful piece of information for a technician diagnosing it remotely or in person, and resetting power without recording it means starting the diagnosis blind.