Potterton Assure E430 / 166 fault code: temporary water-pressure fault

Plain E430 / 166 on a Potterton Assure is listed by the manufacturer as a “Water pressure temporary fault”. The boiler has detected a pressure condition it cannot currently accept and has paused or stopped operation.

“Temporary” is the manufacturer’s classification, not permission to ignore the code. If it returns or the pressure reading behaves unusually, the system needs professional attention.

What does plain E430 / 166 mean?

A sealed heating system needs water within a suitable pressure range so heat can be circulated safely. The boiler monitors that condition. Plain E430 / 166 means the pressure or pressure information has temporarily fallen outside what the control system expects.

The code does not reveal the cause. It does not prove there is a leak, a failed pressure sensor or one particular component problem. An engineer needs the displayed reading, system behaviour and fault history.

Which Potterton Assure models use this code?

The manufacturer’s current error-code table includes Potterton Assure Combi and System boilers in the group where plain E430 / 166 means a temporary water-pressure fault.

Fault codes are model-specific. Confirm the exact model from accessible paperwork or the outside label and do not transfer this meaning to an unrelated appliance.

Why the display symbol matters

The manufacturer lists two versions of E430 / 166 for this model group:

• Plain E430 / 166: water pressure temporary fault.
• E430 / 166 with the crossed-flame symbol: water pressure test failed.

The crossed-flame symbol identifies the second display variant. It does not mean the boiler has a visible flame problem. Photograph the entire display so the engineer can see which version you have.

What might you notice at home?

The boiler may stop providing heating, hot water or both. The fault may clear and return. Other useful observations include:

• the visible pressure is different from its usual reading;
• the reading changes significantly as the system warms or cools;
• the code appears after radiators were bled;
• the heating system was recently drained or worked on;
• there are visible drips around accessible pipework; or
• the boiler restarts but soon shows E430 / 166 again.

None of these observations is a diagnosis. A normal-looking gauge does not prove that the pressure information reaching the controls is correct.

Will a temporary fault clear by itself?

It may clear if the condition was brief, but that does not guarantee the cause has gone. A recurring fault, changing pressure or repeated loss of heating should not be managed with endless resets or repeated filling.

If the display clears, continue to observe the normal external gauge. Arrange a repair if the code returns or the reading continues to behave unusually.

Safe things you can check

Record the full display

Take a photograph showing the code and whether the crossed-flame symbol is present. This distinction changes the manufacturer’s wording.

Read the visible pressure

Note the normal gauge or display without opening the boiler. Record whether the system is cold or has recently been running, because temperature can affect the reading.

Look for obvious water

From a safe position, check beneath the boiler, near accessible pipework and around radiators for visible drips or pooling. Do not dismantle fittings or investigate inside the casing.

Remember recent system work

Tell the engineer if radiators were bled, the system was drained or other heating work took place before the code appeared. That timing can help without proving a cause.

Follow only the exact user guide

If the Potterton Assure guide gives a homeowner pressure or reset procedure, follow it exactly. Do not guess which valves to use or improvise a filling connection. Stop if the code returns.

What should you not do?

• Do not remove the boiler casing.
• Do not repeatedly add water to chase the gauge reading.
• Do not improvise a filling loop.
• Do not adjust internal pumps, valves or sensors.
• Do not operate the expansion vessel or relief valve.
• Do not try to repair a leak inside the boiler.
• Do not keep resetting the appliance.

Water-pressure faults can involve hot water, mains electricity and gas-related equipment. Internal work belongs to a suitably qualified Gas Safe registered engineer.

What the engineer will need to establish

The engineer can check whether system pressure is genuinely outside the expected range, whether the boiler’s reading is reliable and why the condition occurred. They can examine the relevant parts safely without replacing components from the code alone.

Give them the exact display variant, visible pressure, whether the system was hot or cold, any visible water, recent work and whether the fault cleared or returned.

Quick answers

What does plain Potterton E430 / 166 mean?

It means a temporary water-pressure fault on the Potterton Assure model group.

What does the crossed-flame version mean?

The manufacturer lists E430 / 166 with the crossed-flame symbol separately as “Water pressure test failed”.

Does temporary mean it is safe to ignore?

No. Arrange a repair if the code returns or the pressure behaves unusually.

Can I add water to the system?

Only follow the exact homeowner instructions for your model. Do not improvise or repeatedly refill the system.

What should I tell the engineer?

Share a photo of the full display, the visible pressure, whether the system was hot or cold and any recent work or visible water.