Truma Water Heater: “W27”
warning RV water heater fault codes
What it means
Water circulation pump running dry. The internal circulation pump is not detecting adequate water flow, usually because air is trapped in the lines or the unit is not fully filled/vented.
Most likely causes
- Air trapped in the hot water lines most likely
- AquaGo not fully filled with water after winterizing/draining common
- Low fresh water level in the tank common
- Closed valve or blockage restricting flow less common
Safe checks you can do yourself
- Ensure the fresh water tank has water and the pump is on
- Open each hot water faucet one at a time and let it run several extra seconds to bleed out air
- Start with the faucet closest to the heater, then work through the rest of the rig
- Confirm the AquaGo was properly filled after any draining or winterization
How to reset / clear W27
- After purging air and restoring flow, switch the unit off and back on at the control panel
- The warning should clear once steady water flow is detected
When to call a technician
The warning persists after the system is confirmed full of water and all air has been bled, which can indicate a failing circulation pump.
Applies to
Truma AquaGo basic · Truma AquaGo comfort · Truma AquaGo comfort plus
FAQ
What does Truma Water Heater code "W27" mean?
Water circulation pump running dry. The internal circulation pump is not detecting adequate water flow, usually because air is trapped in the lines or the unit is not fully filled/vented.
How do I reset Truma Water Heater W27?
After purging air and restoring flow, switch the unit off and back on at the control panel The warning should clear once steady water flow is detected
What is the most common cause of W27 on a Truma Water Heater?
The most likely cause is air trapped in the hot water lines.
Related · Truma water heater
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Sources
- Tech Tip: Truma AquaGo Error Codes — Truma US official tech tip, code W27 water circulation pump running dry (Truma (manufacturer))
- Truma — Water Heater Model AquaGo Error Codes — Appendix A Error Codes, W27 (Forest River (component manual archive))
Note: Shown as 'W 27' in some documents. On analog panels it is a red LED blink pattern; on CP plus it is an on-screen code.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.