Truma · Truma Combi furnace and water-heater systems

E 44 HBattery voltage below 10 volts

The 12-volt supply is too low for dependable heater operation.

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

What it means

Plain-English answer

Truma defines E 44 H as undervoltage below 10.0 volts. A discharged battery, failed charging source, or severe voltage drop can interrupt the controls and combustion sequence.

Owner-safe checks

What to check first

01
Turn the appliance off and check the RV battery monitor.
02
Charge the battery with the RV's approved charging system.
03
If the battery cannot hold a charge, have it and the charging system tested.

Safety boundary

Stop and call a technician when

Stop if a battery is swollen, hot, leaking, or smells of sulfur.
Seek service if the code returns after voltage is restored.

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