Problem when towing

Because more fuel is usually demanded when towing, it might be worth unplugging/plugging the connector on the fuel rail pressure sensor, usually located on the end of the common rail.

Just a guess but worth checking those connections.

I would be taking it to my local independent garage. A good thinking mechanic is worth his weight in gold. 

Agree with Easy on that one.  I don't know if it helps but I had a similar issue with my Touareg in June when I was towing down to Devon.  Had almost got there when the 'catalytic converter' warning light came on.  (Same symbol as engine management light on other cars).  It went into a garage in Totnes, who were quite good.  They managed to clear the fault code and the warning light went off for a couple of days - but then came back.   Went off again and then came back permanently. Having checked with my local (at home) garage that I was unlikely to be doing any damage by continuing to drive it, I decided to leave the problem until I got home. On my return, my local garage started the diagnosis and pointed out that it could be caused by a number of faults, the most likely being the air mass sensor.  However, I would have to take a risk as electrical items were not returnable, so if it wasn't that, I would have to stand the expense.  So, I told them to go ahead.  The new sensor cost me £180 and took, literally, ten minutes to install. Two months on, I think I can safely say their diagnosis was correct. I have great faith in our local garage which, although technically advanced, still has the old fashioned 'mechanic' approach to problem solving

Oh - whatever happened to the 'good old days', when if there was a problem with my car, I could get my spanners or screwdriver out and fix it??

There was a similar story some time back, in one of the specialist magazines, of a fellow who had a big and heavy twin axle caravan which he towed with a 6 year old Range Rover.  Solo it was fine - hitched it would work for a little time and then it would go into limp mode.  When the vehicle had cooled a little it worked fine, until the limp mode came on.

The article suggested that it could be the blades in his turbo needing cleaning - when under strain I believe the suggestion was that the blades were sticking to the side of turbo housing.

I wonder if this could be your problem - though I am no engineer.  The solution was that he should only run the car on premium grade diesel and purchase some specialist additive to clean out the turbo, with the warning that it could take a few weeks and 1000 or more miles for it to work.

Te article said that it did and no further problems experienced.

Thanks very much for your replies, I do appreciate all you have said and I have had a little chat to a couple of local mechanics, one who suggested possibly a sensor and the other one mentioned the turbo blades, but thought my model was probably to new for that, but he actually works for Vauxhall and said he will look a bit further into the problem while at work. I am currently using the "super" diesel and while I am waiting for the Vauxhall lad to get back to me, I'll try unplugging/plugging the connector on the fuel rail pressure sensor and purchase a turbo/egr cleaner. I've already put a diesel/injector cleaner through the system.

Again many thanks for your help, comments, and it's nice to know I'm not the only one who has had this problem.

I read somewhere a few years ago that the 2.2 diesel from Vauxhall was most troublesome and due to complaints from customers over many years Vauxhall dropped it out of their vehicle range. sorry but personally I don't think it was a good car.   

We had a Vectra with the 2.2 engine some time ago, and it did occasionaly do that but always recovered if you switched the engine off and restarted it. The garage reset the computer and this cured it.

The engine management light came on our Vauxhall Antara when pulling our caravan today. It has done it before and it was the Emissions valve but we had the car remapped which now ignores the emissions valve. Today it went not limp mode again but note sure why. I guess I will have to get a mechanic to test it?