An error code is the boiler telling you something specific. Most are not disasters, but a few are urgent. Here is how to tell them apart.
The tables below cover common codes on four popular makes: Worcester Bosch, Vaillant, Baxi and Ideal. Codes vary between models, so if what you see does not match, check the manual for your boiler.
If you smell gas at any point, do not touch any switches or use a naked flame. Leave the property and call the National Gas Emergency Service on 0800 111 999 before doing anything else. Our guide on what to do if you smell gas covers the steps in full.
Never attempt a repair on the gas side of a boiler yourself. Most boiler repairs need a Gas Safe registered engineer.
Quick guide by type of fault
Whatever the make, the kind of fault tells you what to do next.
You can usually sort it yourself: low pressure, a frozen condensate pipe, or a boiler that simply needs resetting.
Call an engineer: ignition faults, sensor failures and fan errors.
Urgent: gas valve errors need an engineer promptly. A smell of gas is an emergency: do not touch switches or use a naked flame, get out, and call 0800 111 999.
Worcester Bosch
| Code | Meaning | Action |
|---|---|---|
| EA | Ignition failure | Call an engineer |
| E9 | Safety cut-out, overheating protection | Call an engineer |
| D5 | Low water pressure | Top up the pressure |
| A1 | Condensate pipe blocked or frozen | Thaw the pipe |
| C6 | Fan not running at correct speed | Call an engineer |
| E2 | Temperature sensor fault | Call an engineer |
| CE | Pressure sensor fault | Call an engineer |
Vaillant
| Code | Meaning | Action |
|---|---|---|
| F22 | Low water pressure, dry fire protection | Top up the pressure |
| F28 | Ignition failure on start | Call an engineer |
| F29 | Flame lost during operation | Call an engineer |
| F75 | Pump or pressure sensor fault | Call an engineer |
| F61 | Gas valve control fault | Urgent, call an engineer |
| F62 | Gas valve shut-off delay fault | Urgent, call an engineer |
| F83 | No temperature rise with burner on | Call an engineer |
Baxi
| Code | Meaning | Action |
|---|---|---|
| E119 | Low water pressure | Top up the pressure |
| E133 | Ignition lockout, gas supply issue | Call an engineer |
| E125 | Circulation fault, pump issue | Call an engineer |
| E128 | Flame lost during operation | Call an engineer |
| E160 | Fan speed fault | Call an engineer |
| E168 | Multiple faults detected | Call an engineer |
Ideal
| Code | Meaning | Action |
|---|---|---|
| F1 | Low water pressure | Top up the pressure |
| F2 | Flame loss or ignition issue | Call an engineer |
| F3 | Fan fault | Call an engineer |
| L2 | Ignition lockout | Call an engineer |
| L6 | False flame detection | Call an engineer |
| LC | PCB communication error | Call an engineer |
What you can safely do yourself
Topping up low pressure
Low pressure is the most common fault behind a code, and one of the easiest to fix.
- Find the filling loop, usually underneath the boiler.
- Open both valves slowly.
- Watch the gauge rise to between 1 and 1.5 bar.
- Close both valves fully.
- Reset the boiler if the code has not cleared.
If it drops again within weeks, you have a leak. Our guide to a boiler losing pressure covers where to look.
Thawing a frozen condensate pipe
Common in cold weather, when the condensate pipe running outside freezes and the boiler shuts down.
- Find the condensate pipe: white plastic, running from the boiler to outside.
- Pour warm rather than boiling water over the frozen section, or hold a hot water bottle against it.
- Reset the boiler once the pipe has thawed.
Insulating the pipe prevents it happening again.
Resetting the boiler
Do this after fixing a simple problem such as low pressure.
- Find the reset button, usually marked with a flame symbol or the word reset.
- Press and hold it for three to five seconds.
- Wait for the boiler to attempt ignition.
One important limit: if you have reset three times and the error returns, stop. Repeated resets on a genuine fault can cause further damage.
Call immediately if
- You smell gas, in which case call 0800 111 999 first
- The boiler is making loud banging noises
- Water is leaking from the boiler
- The same error returns after resetting
- The code relates to the gas valve or flame detection
- The boiler is very hot to touch or overheating
- There is black staining around the boiler
Small problems become expensive repairs when they are left, so do not live with a code that keeps coming back. A Gas Safe engineer can find the cause and give you the price of the boiler repair before any work starts.
Frequently asked
How much does it cost to fix a boiler error code?
It depends entirely on the fault. A pressure problem may need nothing more than a visit. Sensor replacements are moderate. Major components such as a PCB or heat exchanger are considerably more. We diagnose before quoting, so you always know the figure before we start.
Why does my boiler keep losing pressure?
Repeated pressure loss means a leak somewhere. It could be a radiator valve, a small pipe leak, or a passing pressure relief valve. Topping it up weekly is managing a symptom. The leak needs finding.
Should I replace my boiler if it keeps showing errors?
Not necessarily, since many codes are straightforward fixes. But if it is over ten to twelve years old and failing regularly, and a repair costs more than about half a new install, replacement usually makes better sense. We will give you both numbers.
Can I fix an ignition error myself?
No. Ignition faults involve gas components, and by law any work requiring the boiler casing to be removed must be done by a Gas Safe registered engineer. Faulty electrodes, gas valve problems and blocked burners all need proper diagnosis.