Truma Water Heater: “W45H”
warning RV water heater fault codes
What it means
Electric (230 V) heating warning on Combi E models: the heater is set to use the 230 V AC element but no mains voltage is present, the 230 V fuse has blown, or the overheating protection on the electric side has tripped. Gas heating may still work while this warning is shown.
Most likely causes
- No shore-power / 230 V AC supply connected or available most likely
- Blown 230 V fuse for the heating element common
- Overheating protection (thermal cut-out) on the electric element has tripped common
Safe checks you can do yourself
- Confirm the RV is connected to a working mains/shore-power source and the breaker is on.
- Check that the 230 V supply is actually live (other AC outlets working).
- Switch to gas mode to confirm the heater otherwise functions.
How to reset / clear W45H
- Restore the 230 V supply or replace the 230 V fuse per the Combi operating instructions.
- If the overheating protection tripped, reset it following the Combi operating instructions after the unit has cooled.
- Reselect electric or mix mode at the CP plus panel.
When to call a technician
Mains power is confirmed present and the fuse is good but the warning persists, or the overheat protection keeps tripping.
Applies to
Truma Combi 4 E · Truma Combi 6 E · CP plus control panel
FAQ
What does Truma Water Heater code "W45H" mean?
Electric (230 V) heating warning on Combi E models: the heater is set to use the 230 V AC element but no mains voltage is present, the 230 V fuse has blown, or the overheating protection on the electric side has tripped. Gas heating may still work while this warning is shown.
How do I reset Truma Water Heater W45H?
Restore the 230 V supply or replace the 230 V fuse per the Combi operating instructions. If the overheating protection tripped, reset it following the Combi operating instructions after the unit has cooled. Reselect electric or mix mode at the CP plus panel.
What is the most common cause of W45H on a Truma Water Heater?
The most likely cause is no shore-power / 230 v ac supply connected or available.
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Sources
- Truma CP plus Operating Instructions — Troubleshooting guide for Combi gas heater (H) — CP plus operating instructions p.17, fault code W45H (Truma (OEM-hosted, Imperial Outdoors))
Note: European manuals state 230 V; North American Combi E units use 120 V AC and the equivalent warning is described in the US tech tip. Only applies to Combi 'E' (electric/mix) variants.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.