Boiler
151
Error code 151 on a Potterton boiler indicates a fault with the gas valve — specifically that the boiler’s control board is detecting an issue with the gas valve circuit or its operation. This is a serious fault that prevents the boiler from firing and requires prompt attention from a Gas Safe registered engineer.
What does this error mean?
The boiler’s control board monitors the gas valve electronically to confirm it opens and closes correctly when a heating or hot water demand is made. Error code 151 means the board has detected an unexpected signal — or no signal at all — from the gas valve, causing the boiler to lock out as a safety precaution. In short, the boiler cannot confirm the gas valve is working safely, so it shuts down rather than risk a dangerous situation.
Est. repair cost
£250–£450 for gas valve replacement (parts + labour); £180–£350 for PCB replacement — Gas Safe engineer required for all work
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first: confirm other gas appliances (hob, gas fire) are working normally. If you have no gas anywhere, contact your gas supplier — this is not a boiler fault.
Perform a boiler reset: locate the reset button on your Potterton boiler (usually a button or switch on the front panel, marked with a flame or reset symbol), hold it for 3–5 seconds, and wait for the boiler to attempt a restart.
Wait and observe: if the boiler fires up and runs without returning code 151 within 30 minutes, a temporary gas supply issue may have been the cause. Monitor it over the next 24 hours.
If code 151 returns immediately or the boiler fails to fire: do not attempt further resets — repeated unsuccessful resets will not fix an underlying gas valve or PCB fault and can mask important diagnostic data.
Do not attempt to inspect, remove, or tamper with the gas valve yourself. Gas valve work is notifiable work under Gas Safety (Installation and Use) Regulations 1998 and must only be carried out by a Gas Safe registered engineer.
Call a Gas Safe registered engineer and tell them the exact error code (151) and your boiler model — this allows them to bring the correct parts and diagnose efficiently.
📞 When to call a professional
Call a Gas Safe registered engineer as soon as the reset fails to clear code 151, or if the code returns within a short period. Tell the engineer: ‘My Potterton boiler is showing error code 151, which I understand relates to a gas valve fault.’ Do not continue resetting the boiler repeatedly — if there is a genuine valve fault, this will not resolve it and could complicate diagnosis.
⚖️ Repair or replace?
A gas valve replacement on a Potterton boiler typically costs £250–£450 all-in (parts and labour), while a PCB repair or replacement runs £180–£350. If your boiler is over 10–12 years old, it is worth getting a like-for-like repair quote alongside a new boiler quote — modern A-rated condensing boilers can significantly reduce energy bills, and manufacturers’ parts availability for older Potterton models can be limited. For a boiler under 8 years old in otherwise good condition, repair is almost always the right call.