Overview
Error code E55 on Potterton Promax Ultra / Gold / Titanium boilers means the boiler has detected that a calibration or re-calibration routine is required. Calibration typically refers to the boiler’s combustion or sensor settings being out of tolerance — the boiler can require adjustment of sensor offsets or gas/air settings so burners and controls operate correctly. This code is usually a service-related prompt rather than a single simple part failure; it often appears after sensor drift, component replacement, a power interruption, or when the control electronics decide the appliance needs re-setting to safe operating parameters. Severity is moderate. E55 does not usually indicate an immediate safety-critical failure like a gas leak, but it can prevent the boiler from operating properly: you may lose heating and/or hot water or the boiler may repeatedly lock out until calibration is completed. Because calibration often requires specialist tools (flue gas analyser, test equipment) and knowledge of burner and gas valve adjustments, this is generally not a DIY repair. Some basic checks and a power reset can clear spurious faults, but accurate calibration and any work on gas, combustion or internal sensors should be done by a Gas Safe registered engineer.
Possible Cause: Calibration required
Troubleshooting Steps
Safety precautions:
- Do not attempt to access the burner, gas valve, or flue components. Working on gas appliances is dangerous and must only be done by a qualified Gas Safe engineer.
- If you smell gas, evacuate the property, turn off the gas supply at the meter if safe to do so, ventilate and call the gas emergency service immediately.
- Switch off the boiler and isolate electrical power before doing any visual checks. If you are unsure, call a qualified engineer.
Initial homeowner checks you can do safely:
1. Note the exact code (E55) and any other displayed codes or LEDs — write down when the code appeared and what was happening (e.g., after a power cut, after servicing, during a heating demand).
2. Try a basic reset: switch the boiler off at the main switch or isolate, wait 30 seconds, then switch back on. Some sensor/calibration warnings clear if they were transient.
3. Check system water pressure on the pressure gauge. If pressure is very low (<1.0 bar) or very high (>2.9 bar) top up or bleed down to the recommended range (~1.0–1.5 bar) as described in your user manual. Low or high pressure can cause other faults that confuse diagnostics.
4. Inspect the flue terminal outside for obvious blockages (bird nest, debris). Do not block or obstruct the flue; if you see an obstruction, do not run the boiler and call a Gas Safe engineer.
5. Ensure any external room thermostat or programmer is calling for heat — sometimes communication faults or settings can be misread as other faults.
Specific diagnostic and next steps (homeowner-friendly):
1. After the reset and the checks above, if the E55 remains, do not try to adjust internal controls or gas/air settings yourself. E55 is commonly a prompt for a calibration/service routine that requires specialist equipment.
2. If the boiler has recently had parts replaced (PCB, sensors, pump, or gas valve) or had power supply issues, mention this to the engineer — those events commonly trigger a requirement to re-calibrate.
3. Check for any accompanying fault codes (e.g., flame fail, sensor faults, pressure faults). If there are multiple codes, list all of them as they help diagnose the root cause.
4. If the boiler is still under warranty or you have a service contract, contact the installer/manufacturer or your service provider and quote E55 and the model (Potterton Promax Ultra / Gold / Titanium combi or system).
5. If you have no service contract, book a visit from a Gas Safe registered heating engineer and tell them E55 is displayed. The engineer will normally: run the boiler through its service/calibration routine, use a flue gas analyser to check combustion and adjust gas/air settings if needed, check and, if required, replace or recalibrate temperature sensors or the PCB, and verify safe operation and emissions.
When to call a professional immediately:
- If the boiler will not operate (no heating/hot water) and the basic reset and pressure checks did not help.
- If you smell gas or see signs of combustion irregularity (soot, unusual smells at the flue) — evacuate and call emergency services.
- If E55 is persistent after simple checks, or if the engineer needs to carry out calibration or work on gas components.
Information to give the engineer when you call:
- Boiler model and serial if available, the displayed fault code E55, any other codes noted, when the code first appeared, recent work or electrical interruptions, and the results of your basic checks (pressure, flue clear, reset tried).
Final note:
E55 usually indicates a service/calibration task rather than a simple part swap. A qualified Gas Safe engineer should perform the calibration and any internal adjustments. Avoid attempting gas or combustion adjustments yourself — leave it to the professional to ensure safe, legal and efficient operation.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Potterton Promax Ultra, Gold/Titanium Combi & System.