CEM diagnosis and repair Volvo S40
 

Hi.

Can anyone recommend a company in the UK that can test and repair a CEM unit? My car is a late 2009 Volvo S40 2L diesel.

Basically the car refused to start on one occasion with the immobiliser being activated with a further 'Brake failure - stop safely' messsage apprearing on the dash. I managed to get it started by running a jump lead from the battery to a bare surface on the engine bay. This seems to indicate an earth fault somewhere...but a mechanic suspects the CEM unit is giving bother.

Incidently, the car also completely stopped running (apart from ticking over), while I was driving! the same messages pinged up. It was a bit of a hairy moment to say the least, as I could only just about coast into a lay-by :(

Help is appreciated.

Dealer will give a firm diagnosis. Typically they charge an hours labour, a flat fee, regardless of whether it takes 25 minutes or 3 hours to suss the fault.

Most specialists will charge as long as it takes to do the diagnosis, so it could well end up costing more there than at a dealer if the fault is not identified quickly. Best case scenario is it wouldn't be a great deal cheaper than the dealer, so there isn't much argument in favour of trying to save pennies at the diagnosis stage.

Once you have an authoritative diagnosis you can then make deicisons on what to do or where to take it.

The CEM is the last thing it will be ...

Best get the system diagnosed professionally rather than by someone not familiar with it Guessing .. You suggested the earth lead for the battery that is the first place to start .. 👍

Hello thanks for the advice. Any idea what a Volvo dealership fault diagnosis might cost? I would like an idea before calling them.

My local dealer its £130ish plus VAT, but thats regardless of whether it takes 10 minutes or all day.

An independent (you really want a specilist, not merely an indy) will have a lower hourly rate, but if it takes all day thats 8 or 9 hours plus VAT.

As Clan suggests, there may be a few things worth checking before getting to that stage, such as your suspicionsabout an earth fault. The sun is shining, its warm outside, no better time to go have a play.

A dealer will charge the £130 ish an hour for diagnosis they shouldn't take much longer than that to determine what is going on . It might take an independent all day as they don't have all the knowledge or experience , tools or back up the dealer has .

Thanks. Im going to give Volvo a call in the morning to get a price as I tow a caravan with this car. If it fails mid flight again, this time with a caravan in tow, that could be disasterous, so have to bite the bullet :( Ill update on the diagnosis here later.

I checked for earth faults and found nothing btw

Volvo Belfast - £90/hour for diagnosis

They should be well aware now what this problem is and its cure , it has been around for about 12 years now , only occasionally will they get a case but they should know . They will have network communication fault codes as well as other obscure ones .