I have the above problem and cannot find any information as to what the problem is.

Can anyone help?

Have you tested the voltage of your car battery?

I have just put a new battery on and i checked with a meter after installation and it

was reading 12.66

You said it won't start. Does it crank over, or is it silent and you hear a clicking noise?

and what does this mean? "Aux. Heater 0% displayed..."??

Engine wont crank, instrument cluster flashes yellow, goes off and then comes back and thats when

the information display on the instrument cluster comes up with Aux heater 0%

Does the red immobilser LED flash? It sounds as if you may have the infamous Focus instrument cluster fault.

There are numerous threads on the forum if you do a search. Basically, Focus of your generation used lead free solder in the instrument cluster, however, over time, this deteriorates & cracks, giving all sorts of electrical gremlins.

The solution is relatively easy as loads of companies specialise in the repair of the cluster, and it's a sub £100 job.

Have a look at this thread... I'm sure some other members may chip in either confirming my quick diagnosis, or, of one of their own.

 

This isn't quite that simple. We had the problems (engine malfunction - display irregularities) and sometimes unable to start car. Learnt about

the instrument cluster problems, and the way of clearing this by thumping the dashboard above the instrument cluster. This worked until that display

of aux heater 0%. The car would not respond to thumping. Decided to get the cluster repaired, on inspection they could not repair so we went for a new cloned unit. This was fitted yesterday along with new battery today and still we are no further forward and I cannot find any information on that display

of Aux heater 0%

 

Now, you left alot of that information out of your 1st post LOL Anything else we should know about?

So, your new 'cloned' cluster has never worked then?

The aux heater warning shouldn't make any difference.  It's basically just a tick box that hasn't been unticked on your replacement cluster.

My own Mk2 had this warning at every start when I bought it at 6 years old.  No idea how the previous owners had ignored it for 6 years!

I just unticked it using ELMConfig.

I didn't go through the whole history as everything seemed to revolve round that display message, so I was trying to find out

more about that. As to the other point about unticking on my cloned unit does not explain why the car will not start with that message 

displayed on the original and the cloned unit.

7 minutes ago, Chris Kember said:

.. As to the other point about unticking on my cloned unit does not explain why the car will not start with that message 

displayed on the original and the cloned unit.

I believe that from @TomsFocus post, that warning message is a red herring and nothing to do with why the car won't start...

Were you told why your original cluster could not be repaired?

Fair point.

As it's the same on both clusters then it's likely to be a GEM fault instead.  (Interior fusebox)

This seems to be a glitch specific to 2008 models.  I've never seen the aux heater message on any other year Focus, in the UK at least.

One of the reasons I joined this forum was while researching the problems I came across a forum article which referred to a person

who parked up in a Tesco Store no problem only to come out and the car wouldn't start and that message had appeared. How can I

check out if my GEM unit is ok?

Sorry, I misread the title as 'Aux Heater Off' instead of '0%'.

The Off message can be ignored as a glitch on 2008 models.  The 0% is not the same message and does seem to prevent a start.

Either way, UK spec Mk2.5's don't have an aux heater fitted.  They were only fitted to these in colder climates.  

You can check the GEM visually by removing the plugs and checking for any signs of damp or corrosion around the pins.  If it looks fine then it'll need to go to an electronics specialist to be checked internally, as with the cluster.

I've just had a quick check of the other posts on this myself and none of them seem to get repaired which is odd. 

If it was my car, I might be tempted to see if the fuse is fitted for the aux heater - and remove it if so.  Then disconnect the battery for half an hour before reconnecting and trying again.  That's purely a stab in the dark though.

My first thoughts was to disable the aux heater and so on checking it would appear that F21 was the fuse position for a 20amp fuse.

On checking the fuse box in the engine compartment there was no fuse fitted. Further to my last post I rechecked that forum post back from 2018

he said that he managed to bump start the car but then lost his lights, dash etc. and could not restart the car afterwards. Do you think this is a further

indication that the GEM unit is the culprit?

12 hours ago, Chris Kember said:

My first thoughts was to disable the aux heater and so on checking it would appear that F21 was the fuse position for a 20amp fuse.

On checking the fuse box in the engine compartment there was no fuse fitted. Further to my last post I rechecked that forum post back from 2018

he said that he managed to bump start the car but then lost his lights, dash etc. and could not restart the car afterwards. Do you think this is a further

indication that the GEM unit is the culprit?

Yes, I'd still be looking at the GEM.  The alternative would be a loose or corroded loom plug somewhere behind the dash but that could be very difficult to find.

There is one more potential easy fix that I've thought of, and that would be the ignition switch located at the far end of the barrel, assuming it's a keyed ignition.  Sometimes the switches fail which leaves them half way between positions 1 & 2 instead of moving all the way to 3rd position.  That can cause some very odd electrical issues and might be worth a check.

I checked the ignition as you described and the key went round to 3 position no problem. I thought (as you previously mentioned it)

disconnecting the battery and leaving it for a while might possibly clear what was triggering the immobiliser. This had no effect.

Tomorrow I was going to take the Gem unit off and see how it looks visually on the outside

19 hours ago, Chris Kember said:

I checked the ignition as you described and the key went round to 3 position no problem. I thought (as you previously mentioned it)

disconnecting the battery and leaving it for a while might possibly clear what was triggering the immobiliser. This had no effect.

Tomorrow I was going to take the Gem unit off and see how it looks visually on the outside

It's the ignition switch that breaks, not the key barrel.  It's a separate part attached to the far end of the barrel.  Looks like this:

 

Would I have to remove the switch or am I able to check it in-situ?

1 minute ago, Chris Kember said:

Would I have to remove the switch or am I able to check it in-situ?

If the plug is at an accessible angle then you could leave it in situ, but it's only clipped on anyway.  Will need to remove the plastic steering column cowling first.  That's just clipped together top & bottom and can be separated using a flatblade screwdriver in the 'front' holes, visible with the wheel turned one quarter.  The switch itself needs to be tested with a mulitmeter to check the correct pins are getting powered in the correct key positions.

The switches only cost £10 to £20 so if might be worth just replacing it if testing proves inconclusive.

Hi all. I have a focus 2008 1.8 zetec and mine also always says this on the dash but always starts but every few mins starts to run lumpy but I can override this by putting into neutral while driving and turning the ignition on and off and it’s drives normal again . I’m used to doing it now but not embarrassing when u got passengers . Anyone know whats wrong?