I was towing a caravan at weekend up a steep incline on m1 when the message special systems off appeared on dash and car whent into limp mode. I turned car off and back on again and all was fine until the return journey home where it did same thing again. Is this a common fault or just maybe an electrical gremlin. Apologies for my original post as it was in the wrong area of the forum.

Mine did this and turned out to be a sticky egr valve. Best to get it on the old diagnostic machine tell you straight away if it is the egr.

Egr valves are blanked of.

Mine's currenlty doing the same.

Jury's still out on if it's a sticky egr or sticky turbo actuator rod

Have you a fault reader? RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI

Could be a pipe round the turbo with a slight split. As from what you described happens when the engine is under heavy demand. Need fault codee ideally to point you in the right area

awd man wrote:

Mine's currenlty doing the same.

Jury's still out on if it's a sticky egr or sticky turbo actuator rod

Have you a fault reader?

Got car back from Doug Dransfield and the fault was "turbo over boost". They said because the car has never towed before the variable vain turbo might not be fully working because of a carbon build up. The car is running fine with no caravan on the back and as the caravan is only borrowed I think I'll let the problem develop.

I'm thinking the same.

You might find it's actually a sticking actuator rod at maximum boost, causing this sudden overboost.

Mine's running a modified map, so I'm going to remove the map prior to the next caravan outing and see if I get the same fault. RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI

What we need is for someone brave to try this turbo cleaner on their V8: http://innotecturboclean.co.uk/

There is a pretty genuine video of a guy not connected with the manufacturer's using it here:

So who is going to volunteer?  2008 MY Java Black TDV8 HSE