Potterton E151 Fault Code: Causes, Fixes & Repair Costs
What does the Potterton E151 fault code mean?
The E151 code indicates that the boiler's PCB (Printed Circuit Board) has detected an internal fault — specifically what Potterton classifies as a Type 1 PCB error. The PCB is the control centre of your boiler: every other component — the pump, fan, gas valve, ignition system — takes its instructions from it. When the PCB reports an internal fault, the boiler locks out to protect itself and your home. A closely related code, E152, signals a Type 2 PCB internal fault, which is generally considered a more serious variant of the same underlying problem. If your display is showing E151, the boiler has detected something wrong with its own main circuit board, though in some cases a wiring fault elsewhere can trigger the same code.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Internal PCB component failure Common
Electronic components on the board — capacitors, resistors, microprocessors — can degrade over time and fail. This is the most direct cause of an E151 lockout. The board may show signs of burning, discolouration, or cracked solder joints on close inspection.
- Water or leak damage to the board Common
A dripping heat exchanger, pump seal, or internal pipe joint can send water onto the PCB. Even small amounts of moisture can short-circuit the board or corrode the copper tracks, triggering fault codes including E151.
- Loose or damaged wiring connections Sometimes
A loose plug, corroded connector, or chafed wire between the PCB and another component can cause the board to receive garbled signals and throw an internal fault. Engineers should test individual PCB outputs and wiring looms before assuming the board itself is faulty.
- Power surge damage Sometimes
A sudden spike in the mains supply — from a nearby lightning strike or grid fluctuation — can damage sensitive electronics on the PCB, as well as other components such as the fan or ignition module. The PCB may then report an internal fault even if the physical board looks intact.
- Cracked or physically damaged board Rare
Mechanical stress, vibration over many years, or a previous heavy-handed repair can crack the PCB substrate. A cracked board will almost always need replacement rather than repair.
How to fix it
- Reset the boiler once or twice DIY safe
Locate the reset button on your Potterton's control panel — on most Promax and Performa models it is a clearly labelled button or held symbol on the display fascia. Press and hold for 3–5 seconds until the boiler attempts to restart. If it lights and runs normally, monitor it closely over the next hour. If E151 returns immediately or after a short time, do not keep resetting — repeated resets will not resolve a genuine PCB fault and can mask other issues.
- Check for any obvious water leaks near the boiler DIY safe
Look around and beneath the boiler casing for signs of drips, damp patches, or rust staining. If you can see an active leak, turn the boiler off at the programmer or thermostat and note the location to tell your engineer. Do not attempt to open the boiler casing yourself.
- Confirm the mains electricity and gas supply are working DIY safe
Check that other appliances in the home have power and that the gas supply is active — try a gas hob ring if you have one. A power cut or gas interruption can sometimes cause a fault code to appear on restart. If supplies are normal, the fault is internal to the boiler.
- Have a Gas Safe engineer inspect the wiring and PCB outputs Gas Safe engineer
A qualified engineer will remove the boiler casing, visually inspect the PCB for signs of burning, corrosion, or cracked solder joints, and use test equipment to check the outputs from the board to components such as the pump, fan, and gas valve. This step rules out a wiring fault before the board itself is condemned — saving unnecessary parts costs.
- PCB repair or replacement by a Gas Safe engineer Gas Safe engineer
If the board is confirmed faulty, the engineer will either source a replacement PCB (Potterton Promax and Performa boards are widely available from UK heating merchants) or, in some cases, arrange for the board to be professionally repaired — which can be cheaper than an outright replacement. Only a Gas Safe registered engineer should carry out this work. Once replaced, the engineer will commission the boiler and check all functions before leaving.
- If the boiler is old or repair costs are high, discuss replacement DIY safe
If the repair quote approaches or exceeds £500, or your boiler is more than 10–12 years old, ask the engineer for an honest assessment of whether replacement makes better long-term sense. An older boiler may have other worn components that will fail soon after a PCB repair, making a new, warrantied boiler the more economical choice.
Parts you may need
- Replacement PCB (Potterton Promax / Performa) · from £220
- PCB professional repair service · from £130
- Wiring loom / connector harness · from £45
- Engineer diagnostic / inspection visit · from £80
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £250–£550, depending on the underlying cause.
Frequently asked questions
What is the difference between Potterton E151 and E152?
Both codes point to an internal PCB fault, but they represent different fault types logged by the board. E151 is a Type 1 internal error, while E152 is a Type 2 — generally considered the more serious of the two. In practice, both require a Gas Safe engineer to diagnose and resolve, and the repair process is largely the same: inspect the board, check wiring, and repair or replace as necessary.
Can I fix a Potterton E151 fault myself?
The only DIY steps worth trying are a single reset and a visual check for obvious leaks. Everything beyond that — opening the boiler casing, testing PCB outputs, replacing components — must be carried out by a Gas Safe registered engineer. PCB work involves mains voltages and direct connections to gas-control components, so it is not safe or legal for an unqualified person to attempt.
How much does it cost to fix a Potterton E151 fault in the UK?
Most people with this fault pay somewhere between £250 and £550 in total, depending on whether the PCB can be repaired rather than replaced and on regional labour rates. Repairs typically cost £150–£250 all-in; a full replacement PCB plus labour usually falls in the £300–£550 range. London and the South East tend to sit at the top of that range. In a small number of cases — for example if water damage has spread to other components — costs can exceed £600, at which point it may be worth getting a new boiler quote instead.
Will a reset fix the E151 error on my Potterton boiler?
Occasionally a transient power fluctuation can cause a one-off E151 display, and a single reset clears it permanently. However, if the fault reappears within a short time — or immediately — a reset will not solve the underlying problem. Resetting a boiler with a genuine PCB fault repeatedly will not help and may delay a proper diagnosis. Call a Gas Safe engineer if the code returns after one or two resets.