Truma · Truma Combi furnace and water-heater systems

E 43 H12-volt supply exceeds 16.4 volts

The Combi detected excessive DC voltage and stopped to protect its electronics.

Published by RV Fault Finder · Independent referencePrimary source checked August 2026How this guide is researched →

What it means

Plain-English answer

E 43 H means battery voltage at the appliance is above 16.4 volts. A charger, converter, regulator, or other charging source may be supplying unsafe voltage.

Owner-safe checks

What to check first

01
Turn the Combi off and disconnect nonessential charging sources using their normal controls.
02
Check the RV battery monitor or a permanently installed voltage display.
03
Have the battery charger and converter output checked before restarting if voltage remains high.

Safety boundary

Stop and call a technician when

Do not probe live wiring unless qualified.
Leave the appliance off while the DC supply remains above its normal range.

Primary reference

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 2026