I have the above boiler displaying a 40 60 80 error message on the front panel. From the instruction/user manuals I have deduced that this is a fan/air pressure switch issue. Having had a plumber examine the boiler his suggestion was that the fan needed replacing. I have done this and the problem persists. Using an electrical circuit tester I can tell that the wiring to the fan and air presure switch from the circuit board is good- but there is still no power to the fan itself.

I have checked the fuses on the PCB and all are fine. Through process of elimiation I believe the problem now to be the PCB itself . Does anyone have any further advice before I purchase a replacement PCB?

John Clarkson, June 2008

probably one of two relays jv24sg-kt on pcb is faulty. they are on the right side of pcb near wires connected to pressure switch. i replaced both and works well. i have a chaffoteaux centora i think it's similar.

Salvatore, June 2015

pcb probably. it says fan code but if there is no power going to the fan the fan wont work!!

simon roberts, October 2014

I solve the problem replacing PBC as you said above, with the last and modified model. I wll try to repair the previous PBC if I met an emergency situation...

Many thanks.

Daniel, January 2014

Why dont you all just pay for a gas safe registerd engineer to call. It will save you money on parts that you all chuck at it when not knowing what the fault is

Neil., February 2013

Just had the same problem - faulty PCB
got a new one for £150. It's all sorted

Rosbif, December 2012

Just had same error code with my MX2 24FF boiler says pump running buts its not, can confirm a new pcb fixes the fault I am now looking to replace the relay on the pcb and keep this as a spare.

Iain, May 2012

I have had the same problem 40 60 80 error, traced to relay Takamisawa JV24SG-KT. if you are having problems finding a supplier try www.lumaco.co.uk they stock the exact match £6.50 +vat, next day delivery, removed old and replaced with new, we now have hot water and heating, nice......

richard, March 2011

This is electricity problem. It is reley that is blown. You dont see is it blown or not. You shod open the electricity box lower down, open it, remove cabels, take off the printing plate. Top left side of the printing plate is relay. Model nr is written down there. You should buy the new reley, important that parameters are same.Then let some electric to change it (with soldering iron), put the printing plate back and it works.Problem is that releys are made in China and one day they dont work any more.

Had same problem- fixed, September 2010

try cleaning the venturi above the fan,,, the thing with the silicon tubes attached to it

what ever, January 2010

hi this happened to me before and the fault still comes up 40 60 80 it may not work but blow threw the ventrical valve at the top of the boiler this may help

dave wallis, December 2009

hi can you give me any info regarding my mx2 24ff boiler it frequently trips off displaying a 70 80 error. Or tell me where i can get a manual from.

shaun, November 2009

For anyone thats interested, an alternative to the JV24S-KT relay is KAM LING Pt No KU1T-MF relay. Its footprint is larger, but you can solder some wires to the relay pins then solder the other ends onto the circuit board.
IIRC the JV24 is N/O...the Kam Ling is N/O or N/C, the ones i've got have the N/C pin cut off. I assume that was done by the manufacturers.
Make sure you insulate the soldered wired on the relay, to avoid short circuiting against any other components.

Colin W, April 2009

Never, in twenty seven years as an engineer, have I come across a more unreliable make. THE FAULT FINDING CHARTS ARE NAFF and parts are expensive. My advice. Put a vaillant in.

gasser, December 2008

Check the main overheat stat which is clamped on the right hand side pipe which is a flow pipe facing the boiler. Bridge the overheat stat to test.

I. Sharma, October 2008

I have exactly the same fault with my C&M Britony Combi SE, 40+60+80 flashing.

I checked this out and found that the fan was not running, althought the error code is 'fan on but does not activate air pressure switch'.
I checked the fan with a multimeter, but found it was not being driven (saftey note: it's 240 vac).

Tracing the fan wiring back to the pcb, I found that the fan is driven from a Takamisawa JV24SG-KT relay.
I was quoted £132 for a replacement pcb, so am currently attempting to repair the pcb, by replacing said relay. However, I am struggling to find a supplier of a relay in the UK (Google search lead me here!).

Graham, September 2008

Just had a similar symptom problem overnight with our mx2-30ff. LED's on the front flash to show a "fan on but no pressure" code, but in this case the fan isn't on.

Did some testing, and the relay (jv24s-kt) on the PCB activates and clicks with a 35V coil voltage according to my DMM, which is interesting given that the relay has a 24V coil. There's 240V at one of the relay contacts, but continuity doesn't seem to be made by the relay when the coil activates. Need to do more tests but it seems that the relay contact has failed. I'd definitely not assume that the relays on these boards are working just because they click.

These boilers, which have been discontinued now, seem to be very poor in terms of reliability. About 4 years old and we've had the control board replaced several times already. The flame sensor probes are unreliable and in the past, C&M said that they'd changed to different probes on newer versions, presumably to remedy from one of their various design faults on the unit.

Nick, August 2008

Yeah, the click would suggest it is working, but do check that it actually switches with your meter when you blow/suck

assuming the pump IS running, and the thermister resistance is correct, the hi limit stat continuity is correct, and you have already fitted a new fan, I would be looking at trying a new pcb

T, June 2008

Thankyou, Ive tried the aps by as you advised blowing and sucking into the silicone tubes. There is an evident click each time. Would that suggest that the aps is still in working order and that it is the PCB?

john, June 2008

I would try replacing the air pressure switch, what the fault finding is indicating is that when the air pressure switch is made, it is not returning to its resting position (so signals to the pcb are not correct) so the pcb does not allow the fan to start (as it sees a fault!)

you can test the aps by (very very gently) sucking and blowing into the silicone tube, you should here it clicking and the using a multimeter you can test the switching (be aware if you suck blow hard you will ruin the switch)

T, June 2008