Ideal C0 fault codewhat it means and how to fix it
The board cannot activate the Boiler Chip Card that tells it what model it is fitted to. Ideal's engineer check is whether the small plastic card is in its slot at all.
Take care
Get a Gas Safe registered engineer to look at your Ideal C0
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 C0 means
From about 2012 Ideal stopped configuring Logic boards by dialling in settings and instead plugged a small plastic card into the PCB — the Boiler Chip Card, or BCC — carrying the range and output. A replacement PCB comes blank and the card is transferred to it or bought with it; Ideal's i combi manual says a BCC MUST be purchased with any spare primary PCB for the specific boiler. C0 is BCC Activation Fault: the board has powered up and cannot activate the card.
Ideal's fault-finding frame for it is one line long — ensure the BCC, described as a small plastic part, is fitted to the PCB, otherwise replace the PCB, then reset. The householder guide is shorter still: reset the appliance, and if it fails to operate contact Ideal or a Gas Safe engineer. The 2011 Logic+ printed the same fault as Boiler Type Card Fault on its text screen. Ideal's own installer sequence has the display show c0 briefly when a card is first inserted, so a C0 that clears on reset after work has been done is the board doing what the manual says.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Card not fitted after a board change | The new PCB went in and the chip card stayed in the box, or stayed on the old board. Ideal's note in the replacement procedure anticipates exactly this. | Common |
| Card loose or in upside down | The slot is at the front left of the PCB and the card has a TOP marking. Ideal's C2 frame repeats the orientation note because it is a real way to get it wrong. | Common |
| PCB unable to read the card | When the card is present, correct and seated and C0 persists, Ideal's frame has one answer left: replace the PCB. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£60–£380
Time on site
30 minutes
Reseating or fitting the card that was left out is a short visit, £60–£90. A PCB with its card £250–£380 fitted.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
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Ideal Logic primary PCB
£150–£320Authorised Ideal parts distributor
Price checked 28 September 2026
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Related Ideal fault codes
- F9Get it checkedThe control board has not been told what boiler it is in, or has failed. L9 is the same fault locked out. The 2011 Logic Combi row also covers a gas valve short circuit.Related: electronics and power
- dUUsually simple to fixNot a fault. The diverter valve has been parked in its mid-position for servicing and the boiler is waiting to be told the service is over. Ideal publish the way out.Related: electronics and power
- Blank displayGet it checkedNothing on the screen at all. Ideal's user guides send you to the boiler's switch and the consumer unit first; the installer charts then work from the terminal block to the board.Related: electronics and power
- F7Get it checkedThe mains voltage reaching the boiler has dropped below what the board will run on. Ideal's advice is an electrician or your electricity supplier, not a heating engineer.Related: electronics and power
- L9Get it checkedOn a Logic, L9 is the locked-out form of the unconfigured-board fault F9. On an Isar HE it is something else entirely: a heat exchanger overheat read by the dry-fire thermistor.Related: electronics and power
- SEUsually simple to fixA service reminder, not a fault. The installer set a timer at the last visit and it has run down. Ideal's advice is to contact the installer, who resets it when the boiler is serviced.Related: electronics and power
Own an Ideal boiler? Save it and its codes come first next time.
Related guides
Common questions about Ideal C0
Can I reseat the chip card myself?
It is inside the boiler's control box behind the sealed casing, and the casing is not to be removed by anyone who is not Gas Safe registered. It is also the component that tells the board how much gas to burn. Press reset once as Ideal say; beyond that it is an engineer's five minutes.
Which Ideal boilers use a Boiler Chip Card?
The two-window generation: Logic Combi ES and Code Combi ES, Logic System and Heat of 2012–2015, Logic+ of the same years, Independent C, ProCombi Exclusive, i-mini and i combi. The ESP1 that followed went back to configuring the board through the knobs, which is why its manual has an F9 sequence and no C codes.
What is the difference between C0 and C2?
C0 is the board failing to activate a card; C2 is the board reporting the card itself is wrong or faulty — the wrong output, or one that has failed. Ideal's engineer frame for C2 ends by fitting a new card and, if that does not clear it, a new PCB.
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
- Manufacturer support portal
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.