Thanks Guys, appeciate your input.

Car was bought here in Thailand. Previous to the "warranty repair" I seem to remember seeing 2 sensors but cannot be sure, so that IS interesting. I will check it out with Volvo tomorrow.

OK. assuming I don't need the CAT I need to addrers the poor running of the car. It is OK at low revs and normal driving but if full throttle is applied the car begins to accelerate, enters full boost, then misfires badly with explosions sounding like they come from the exhaust. The fuel economy is poor.

The noise of the exhaust is now intolerable for what is supposed to be a luxury car. I will probably need a new downpipe,and also the pipe to the silencer box, as the garage have cut out the CAT and welded a pipe to each existing pipe. Any recommendations on a suitable box to replace the CAT to silence the roar? It needs to be a commonly available one if possible. How much is a CAT anyway? (I'll probably have an estimate tomorrow but interested in your input from other countries).

All computer codes extracted, relevant or not:

535 turbo regulator valve fault
212 heated o2 sensor
213 what is this?
214ignition RPM sensor intermeittently absent.
443 what is this and is it relevant?
122 likewise

Some of these esp. 214 I guess are clearly relevant but I have no data or service manual on the car - so would appreciate comment and the possible cures. I am reasonablt capable of doing any necessay repairs BTW, serviced all previous cars myself.

I will probably post more appeals for info as the car has been screwed up badly - nothing that can't be put right but at my own expense, sadly :-(

Keith