S-Max limp home.

Post by **pete** » Sun Jun 02, 2013 7:09 pm

A friend has an S max which keeps going into limp home mode. She's had it in to her local garage a couple of times to no avail.

It's a diesel, 5 yrs old low miles but mostly round town. I suggested that it might be the diesel thingy valve, the garage have apparently concentrated mainly n electrical issues.

Any ideas from the collective (look afetr the amazing Xsara success there's always a chance that someone has had the smae problem).

s29ttc · Post by **s29ttc** » Sun Jun 02, 2013 7:45 pm

Yeah I'd clean out the egr valve and see if it helps. Newer diesels need a good blast now and again and maybe the egr valves became clogged toddling about town. Long shot but worth a try, happened on Holly's brothers Sabb limp home mode and smokey exhaust and that was the issue.

robin · Post by **robin** » Sun Jun 02, 2013 9:42 pm

Agreed - rev the knackers out of it - preferably take it for a motorway drive and leave it in 4th so that engine revs are higher than normal at 70mph.

Cheers,
Robin

Edited to add: this is kill or cure - if it's a cracked pipe or turbo weld or similar, then it will probably break

So maybe take a second car for the ride to escort the first one off the motorway when it breaks

BiggestNizzy · Post by **BiggestNizzy** » Sun Jun 02, 2013 9:52 pm

Another vote for egr, guy at works pug did the same.

Post by **campbell** » Mon Jun 03, 2013 12:45 am

not sure if same tech but does it have a DPF?

Failure of sensor for this put our Oct into limp home mode once.

DIY treatment is broadly the same - needs driven hard to burn off soot particles. Audi tech who came out to sort at roadside was brilliant and explained the whole system. Rescued our holiday.

mckeann · Post by **mckeann** » Mon Jun 03, 2013 12:53 am

I provide a 'drive it hard' service for EGR type problems. £45 an hour. Get in touch.

Post by **pete** » Mon Jun 03, 2013 8:53 am

I knew there was a car fix that involved thrashing the car until it got better. Thanks for the advice (it was similar to the advice I gave believe it or not) but you would have thought a garage would have thought of that too...

McApe I'll let her know you are for rent, although that's a very small market.

Doc883 · Post by **Doc883** » Tue Jun 04, 2013 7:39 pm

A women at my work had a diesel Toyota Avensis

and she never revved it above about 2500rpm in any gear. Whilst in the garage for what turned out to be a related problem the mechanic asked her to take him out for a spin and drive the car as she would normally. Advice following drive was to rev it higher to burn of the deposits that had clogged the entire system. As a result she decided to part ex it as she thought it was going to keep breaking down and it was 3 years old and just coming out of warranty. New car, you guessed it Toyota Avensis

111Robin · Post by **111Robin** » Wed Jun 05, 2013 12:44 pm

Tend to agree it'll be the DPF. If it has become choked due to engine not being run for longer periods at higher rev's, the ECU will have been putting it into high burn mode by injecting the DPF fluid into the intake cuasing the engine to run hotter to burn off the carbon in the filter. If the filter is so badly choked that this doesn't work the ECU will keep repeating this process until the fluid tank is empty then it goes into limp home mode. It'll need a new DPF and fluid re-fill , very very expensive. If you have a modern diesel you really have to take it on the motorway or similar every now and then to make sure it keeps the filter clear. Seen it on a Focus recently.

Post by **campbell** » Tue Jun 11, 2013 12:57 am

What's DPF fluid?

I thought the system just set the car to run rich every so often, thus increasing exhaust gas temps to provide the burn-off.

111Robin · Post by **111Robin** » Thu Jun 20, 2013 12:01 am

The fluid causes the exhaust gas temp to increase sufficiently to burn off the carbon in the dpf. It will normally last several years and is supposed to be topped up at certain service intervals. It is very very expensive though and can be a real pita to fill. We borrowed the filler kit and fluid from a ford dealer to do a focus.

Stevoraith · Post by **Stevoraith** » Thu Jun 20, 2013 8:11 am

Pretty sure DPF fluid isn't a universal thing- never heard mention of it on any VAG forums and it certainly isn't mentioned in the service schedule for our Octavia.

Perhaps something only certain manufacturers use.

Scottish Scrutineer · Post by **Scottish Scrutineer** » Thu Jun 20, 2013 8:25 am

I think it is a Ford thing.

Sent from my iPad using Tapatalk
Renny

111Robin · Post by **111Robin** » Thu Jun 20, 2013 8:48 am

It's not just Ford, Peugot, Citroen, VW, Audi all use a DPF fluid. Can't vouch for every single model, but if it has a DPF filter I would assume it also needs a fluid reservoir, they all work on the same principle.

111Robin · Post by **111Robin** » Thu Jun 20, 2013 12:24 pm

Stevoraith wrote:Pretty sure DPF fluid isn't a universal thing- never heard mention of it on any VAG forums and it certainly isn't mentioned in the service schedule for our Octavia.

Perhaps something only certain manufacturers use.

Seems that the VW Touareg TDI, VW Passat TDI, and Audi Q7 TDI use a fluid called AdBlue, other VW/Audi/Skoda engines use a retarded ignition cycle to increase the exhasut gas temperature therefore don't have the AdBlue fluid reservoir

Scottish Elises

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