Overview
Five green flashes on a Baxi EcoBlue Advance / EcoBlue Regular typically indicates a parameter error on the boiler's printed circuit board (PCB). In most documented cases this is a temporary fault where the PCB has detected an unexpected parameter or internal communication glitch. Many of these transient errors will clear themselves after the boiler cycles power or is reset, and no immediate component replacement is required. Severity is generally low if the boiler is otherwise operating normally and the error clears on its own. However, if the 5-green-flash event repeats frequently, is accompanied by loss of heating or hot water, other fault codes, or a locked-out boiler, that points to a persistent PCB, wiring, or sensor issue and you should contact a Gas Safe registered engineer. Basic user actions like performing a controlled reset and checking simple system conditions are reasonable, but do not attempt to access or repair the PCB, gas components, or internal wiring unless you are a qualified engineer.
Possible Cause: Parameter error on printed circuit board (PCB). Temporary error, will self reset
Troubleshooting Steps
Safety precautions:
- If you smell gas anywhere, do not touch the boiler. Turn off gas at the meter if it is safe to do so, leave the property immediately and call the gas emergency number. Do not attempt any DIY.
- Isolate electrical power to the boiler at the external isolator before doing any internal checks. If you are not confident or the task requires opening the boiler case, stop and call a Gas Safe registered engineer.
- Do not try to remove or probe the PCB, gas valve or sealed components. Only visual and external checks should be done by a homeowner.
Initial checks a homeowner can do:
1. Note any other indicators or fault codes displayed and the exact time and frequency of the 5-green-flash event. This information is useful if you call an engineer.
2. Check the boiler pressure on the gauge. Aim for roughly 1 to 1.5 bar when the system is cold. If pressure is below 1.0 bar, follow the manufacturer's instructions to top up via the filling loop, then reset and observe.
3. Look for obvious signs such as frozen condensate discharge pipe in very cold weather, blocked external flue terminal, visible water leaks, or recent power outages which may have coincided with the error.
4. Ensure the gas supply to the property is on and any prepayment meter has credit, but do not tamper with gas fittings.
Reset and basic diagnostic steps:
1. Perform a controlled reset: locate the boiler reset button (or selector switch) and press and hold for 5 to 10 seconds. If your model uses an ON/OFF/SELECTOR switch, move it to R (reset) and hold as per the manual. Wait for the boiler to attempt a restart and watch for the fault to clear.
2. If a reset does not help, isolate the boiler electrically at the mains or the external isolator, wait about 30 seconds, then restore power to force a full power-cycle. Observe whether the 5 green flashes return.
3. If low pressure was identified and you topped up, bleed a radiator to remove trapped air, re-check pressure and then reset the boiler again.
4. If the condensate pipe is suspected frozen (common in cold weather), follow manufacturer advice: turn off the boiler electrically, thaw the condensate pipe safely using warm (not boiling) water or a warm cloth, then restart and reset.
5. If the error occurs alongside other symptoms such as no ignition, strange noises, loss of thermostatic control or repeated lockouts, do not continue to reset repeatedly. Repeated resets can mask an underlying fault and may cause additional wear.
When to call a professional:
- If the 5-green-flash error returns repeatedly or does not clear after reset and power-cycle.
- If the boiler locks out, displays additional fault codes, or you have intermittent loss of heating or hot water.
- If there are signs of electrical faults, burning smells, visible internal damage, or you need internal wiring or PCB inspection.
- If you are unsure about topping up pressure, bleeding radiators, thawing condensate pipes, or any step above.
What to tell the engineer:
- Exact model and serial number if available, the error code description (5 green flashes / parameter error on PCB), when it started, what you tried (reset, power-cycle, pressure top up), and any other symptoms. This helps the engineer prepare the right tools and parts.
Final note:
A one-off 5-green-flash event is commonly temporary and may self-clear, but recurring occurrences or any loss of function should be diagnosed and repaired by a Gas Safe registered engineer. Do not open the boiler casing, probe the PCB, or attempt gas-related repairs yourself.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Baxi EcoBlue Advance / Ecoblue Regular Gas Boiler.