Ideal F12 fault codewhat it means and how to fix it
The pump rotor is jammed. Ideal's remedy is to clear the blockage — on a modern Logic that is an engineer freeing or replacing a sealed pump head, not a screwdriver in a bleed screw.
Take care
Get a Gas Safe registered engineer to look at your Ideal F12
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
What F12 means
F 12 is Pump Rotor Blocked. The Logic Combi2 and its text-screen siblings use an electronically controlled pump that reports back to the board, and when the motor is energised and the rotor does not turn, the board knows and says so. Ideal's remedy is two words, clear blockage, and the Vogue manual's is the same — unblock pump.
The Logic+ user guide of 2023 puts Pump Rotor Blocked on the screen with Contact Installer beneath it, and that is the right reading of the two words: the pump heads on these boilers are sealed, there is no central screw to turn the rotor with, and clearing a blockage means removing the head. The likeliest readings of a jam are a summer's worth of magnetite settling in the pump while it stood idle, followed by a first cold morning; a fragment of debris from the system; or a motor that has failed with the rotor free. Ideal publish only the two-word remedy, so that ordering is this page's, not theirs.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Magnetite settled in the pump over a summer | Black iron oxide sludge from the radiators is magnetic and the pump rotor is a magnet. Leave it still for months and the first start of autumn can find it stuck fast. | Common |
| Debris lodged in the impeller | Flux, jointing compound, a flake of rust or a piece of a failed component upstream. Fitting or emptying a system filter is the long-term answer. | Occasional |
| Pump motor failed | The board cannot always tell a jammed rotor from a dead motor, so a pump that is free and still reports F 12 is being replaced rather than cleared. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£80–£600
Time on site
1 hour
Freeing a jammed head at a visit £80–£130. A new pump fitted £180–£350. A system flush and filter, if the sludge that caused it is dealt with, £300–£600.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Central heating circulating pump
CH-PUMP-15-60£90–£180Plumbing merchant
Price checked 28 September 2026
Magnetic system filter, 22mm
MAG-22£65–£120Plumbing merchant
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Ideal fault codes
- L1Get it checkedThe boiler is not seeing enough water flow through it to run safely, so it has stopped. Usually a pump, an air lock, or a blocked filter.Related: overheat and circulation
- FDGet it checkedNo water flow has been detected. The pump is the prime suspect and this will become an overheat if it is left.Related: overheat and circulation
- L3Get it checkedThe boiler has stopped because it cannot detect water moving through it. Ideal's own steps are to fill the system to 1 bar with it cold, bleed the radiators and try again.Related: overheat and circulation
- L AGet it checkedThe overheat thermostat on an Isar, Icos, Mexico HE or Esprit has tripped and the boiler has locked out. Ideal say hold reset for two seconds; if it recurs, switch off and call the installer.Related: overheat and circulation
- FUGet it checkedThe water leaving the boiler is more than 50°C hotter than the water coming back, which means very little of it is moving. Check the valves are open before anyone condemns the pump.Related: overheat and circulation
- F13Get it checkedThe board has lost proper communication with or control of the pump. Ideal group F13, F15 and F17 as one Pump Fault: check the pump wiring, and if that is sound replace the pump.Related: overheat and circulation
Own an Ideal boiler? Save it and its codes come first next time.
Related guides
Common questions about Ideal F12
Can I free the pump myself?
Not on these boilers. Older pumps had a slotted screw in the middle of the head that let you spin the rotor by hand; the modulating pumps on the Logic Combi2, Logic+ and Vogue do not, and reaching the pump means removing the sealed casing. Ideal's user guide says Contact Installer and means it.
Which boilers show F12?
Logic Combi2, System2 and Heat2 and the i-mini2 as F 12; Logic+ and Logic Max from 2023 and every Vogue Gen2 and Vogue Max as Pump Rotor Blocked on the screen. Earlier Logics have no pump-specific code and show the consequence instead — L1, FU or L3.
Will it happen again?
If the system is dirty, yes. The blockage is a symptom of sludge, and the fix that lasts is a system clean and a magnetic filter on the return. Ideal supply a system filter with the Logic Max and make fitting it a condition of the warranty.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.