Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
N/A | No water flows from any tap even though the pump is running. | Could be an empty freshwater tank, the pump wired in reverse, a disconnected inlet or outlet pipe, kinked pump pipes, a blockage in the pump's inlet or outlet pipe, a blocked pump filter, or an air leak in the pump's suction line. | Check the freshwater tank level; check the wiring against the pump manufacturer's instructions; check the connections and the pipe run; look for blockages starting from inside the freshwater tank; dismantle and clean the filter per the pump manufacturer's instructions; and check the condition of the pipe and its joints between the tank and the pump. | DIY Safe |
N/A | Pump does not run | Could be the pump wired incorrectly, a blown pump fuse, a disconnected battery, a seized or overheated pump, a failed pressure sensing switch, faulty contacts, or faulty wiring connections. | Refer to the pump manufacturer's instructions; check the wiring and replace the fuse with one of the correct rating; check all connections; follow the pump manufacturer's servicing instructions; confirm the plug and socket contacts are clean and making good contact; and check the wiring connections. | DIY Safe |
N/A | Water flows from the cold tap but not the hot one. | Could be a blockage in the hot pipeline, kinked heater inlet/outlet pipes stopping flow, a failed or blocked hot tap, or a jammed heater non-return valve. | Disconnect the pipes and inspect them, check the routing and re-route if needed, disconnect and inspect the tap, or arrange service attention. | DIY Check / Tech Fallback |
N/A | Water flows from the hot tap but the cold tap's flow is reduced. | Could be a kinked cold water pipe stopping flow, a blockage in the cold pipeline, the cold tap not connected, or the cold tap failed or blocked. | Check the pipe routing and reroute if needed, disconnect the pipes after the first connector and check through to the tap, refer to the installation instructions, or disconnect and inspect the tap. | DIY Safe |
N/A | Both the hot and cold taps have reduced flow. | Could be low battery condition making the pump run slowly, newly-fitted taps restricting flow, a pump needing servicing, a partially blocked pump or in-line filter (where fitted), a kinked pump outlet pipe, or a water leak. | Check the battery's state of charge (see the electrical supply note); disconnect the taps and confirm they have at least a 1/4 inch (6.3mm) bore; follow the servicing instructions for the pump; clean the filter and take it apart if that's needed; check the pipe routing and reroute if necessary; and check every water connection. | DIY Safe |
N/A | Reduced flow from either tap | Could be a kinked pipe restricting flow, or a mismatch in tap bore sizes. | Check the routing and reroute if necessary, and make sure the taps match in bore size. | DIY Safe |
N/A | The pump motor runs steadily and won't stop. | The battery voltage may have dropped too low (under 10.5V), or the container may have run dry. | Adjust the switch and/or recharge the battery, and check every connection in the pipework. | DIY Safe |
N/A | The space and water heater won't light (water heater only). | No gas; Air in pipe | Check the gas level in the cylinder, confirm the cylinder valve and gas taps are on, purge the system, and refer to the water heater manufacturer's instructions. | DIY Safe |
N/A | The PSU's reverse polarity light is on while running from a generator. | Certain generator types centre-tap their earth connection instead of earthing neutral directly, leaving both neutral and live conductors sitting around 110V above earth. | Seeing the reverse polarity light while running a generator is a normal quirk with certain generator types. Rather than earthing the neutral conductor directly, this type of generator taps into the earth connection at its centre point instead, leaving both the neutral and live conductors sitting around 110V above earth - and that 110V difference is what lights the neon polarity indicator.
It's usually still safe to keep using the generator, but check its own handbook for confirmation. | DIY Safe |
N/A | Pump not working | Fuse blown or pump turned off | Fit a replacement fuse of the correct rating from the fuse table, then switch the pump on using its button on the control panel. | DIY Safe |
N/A | Fresh water level low warning on control panel | The pump is running and the fresh-water level has dropped below 25% full - only relevant where an on-board tank is fitted. | A message appears on screen along with a 60-second audible beep. | DIY Safe |
N/A | Waste water level full warning on control panel | The pump's on and the waste water tank is full - only relevant where an on-board tank is fitted. | A message appears on screen along with a 60-second audible beep. | DIY Safe |
Frequently Asked Questions
Q: How do I adjust the pressure switch setting on a Truma/Flo-Jet pump?
Begin by removing the cover cap from the pump's end so the pressure adjusting screw is exposed. Don't move it more than a quarter-turn either way from the factory setting - clockwise raises the cut-out pressure, anti-clockwise lowers it. There's a second screw below the cover cap held with threadlock - leave that one alone.
You may need to remove the pump entirely to reach it: drain the water system first, then pull the blue taps out at right angles to the pipework and lift the pump clear.