Truma Combi 4 / 6 series fault codes
The 4 fault codes below are the ones that apply to this Truma furnace family. The other 2 Truma furnace codes in our database belong to different model families — they are listed further down so you do not troubleshoot against the wrong table.
Covered model numbers
Combi 4Combi 4 ECombi 6Combi 6 ECombi Comfort PlusCombi Eco Plus
Not on the list? Check the rating label before you troubleshoot — the code table below will not apply. Where to find it →
Fault codes on the Truma Combi 4 / 6 series
Over-voltage: the supply voltage to the heater is too high (Truma cites above roughly 16.4… E44H warning
Under-voltage: the supply voltage to the heater is too low (Truma cites below roughly 10.0… E112H / E212H danger
Gas/flame fault group: the burner did not ignite or the flame was not detected, and/or com… W18H warning
Warm-air outlet or circulated-air (return air) intake is blocked, so the unit cannot move …
Codes that do not apply to this model
These 2 codes exist on other Truma furnaces. If your unit is showing one of them, it is not from this family — re-check the model number on the label before acting on any of these.
VarioHeat ignition/flame fault: the furnace released gas and attempted ignition but no fla… W25H–W29H
VarioHeat voltage and airflow warnings: W25H = overvoltage above ~16.4 V; W26H = undervolt…
Where the model number is
On the furnace casing itself, reachable through the return-air grille or the exterior access door, not on the thermostat.
Sources
- Tech Tip: Truma Combi Error Codes — Truma (official US site) (Truma Combi error code reference, W18H)
- List of flash codes Combi 4 (E) / 6 (E) — Truma (OEM flash-code list via Dometic RV Centre) (Fault no. 44, under voltage lower than 10.5 V)
- Truma CP plus Error Codes (Combi) — Ember RV (OEM-hosted Truma table) (CP plus error code table, code 18)
All Truma furnace fault codes →
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