Truma Combi 4 / Combi 6 fault codes
The 4 fault codes below are the ones that apply to this Truma water heater family. The other 8 Truma water heater 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 4 / Combi 6
Also documented for: Combi 4 E / Combi 6 E.
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 / Combi 6
Combi cold-weather gas fault: the gas-pressure regulation system has iced up so gas cannot… E211H / E212H warning
Gas-supply / combustion fault group on the Combi: the burner could not run because gas is … W21H warning
Room-temperature sensor warning on the Combi: the CP plus has detected that the room tempe… W42H warning
Roof-window safety warning on the Combi: a window above the heater's exhaust cowl is open …
Codes that do not apply to this model
These 8 codes exist on other Truma water heaters. 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.
No flame detected. The AquaGo attempted to ignite the gas burner three times and could not… W17H
Hot-water mode was selected while the water heater (boiler) is empty. The unit reports the… W27
Water circulation pump running dry. The internal circulation pump is not detecting adequat… W29
Excessive heat demand. The unit is running at full capacity but cannot maintain the target… W30
Risk of freezing. The temperature inside the AquaGo has fallen below roughly 27 F (about m… W31
Decalcification finished. A status message confirming the unit has completed its routine d… W45H
Electric (230 V) heating warning on Combi E models: the heater is set to use the 230 V AC … W255H
Communication/power warning: the heater is not receiving 12 V DC power, or the CP plus con…
Where the model number is
On the data plate behind the outside access door, next to the burner tube — bring a torch, it is often sooted over.
Sources
- Truma CP plus Operating Instructions — Troubleshooting guide for Combi gas heater (H) — Truma (OEM-hosted, Imperial Outdoors) (CP plus operating instructions p.17, fault code W42H)
- Tech Tip: Truma Combi Error Codes — Truma North America (Combi error-code tech tip (E112/E202/E211/E212H))
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