The above advice is spot on,the vehicle is getting on regards mileage so you need everything to be ok including the management light.Other problems are quite common on volvo v70 are noted in HJ car by car report especially the carb valve causing all sorts of problems and a cost of £700 "ouch" the exhaust and cat cause problems as do worn injectors another common v70 problem.

I would guess the the MIL lamp is on because the ECU is registering that the system is generally running too rich or too lean, or is indicating an oxygen sensor or catalyst fault. Unfortunately these type of problems are not always easy to diagnose, but it would help if you could get it hooked up to a scantool. If your car was registered after 1 January 2001 it will be EOBD compliant and so any generic scanner should work. If it were me I would be looking at live data after I'd read the fault codes to see what's been stored, and in particular looking at 'Short Term Fuel Trim' and 'Long Term Fuel Trim' which ideally should both read 0%. If they move up or down it means that the engine is running rich or lean and that the ECU is compensating by either adding or removing fuel by the percentage shown. That I'm afraid is the easy part. It is more difficult to establish why the engine isn't running as it should be. Possible causes include: Faulty oxygen sensor (either pre or post cat), faulty catalyst, faulty MAF sensor, air leak on inlet manifold, blocked air filter, blocked or faulty fuel injector/s, incorrect valve clearances, loss of compression or low fuel pressure.

Also I think there is a lot of mileage in the above advice. Buy some good fuel additive and thrash it up the road immediately before the retest.....

Edited by Railroad. on 02/10/2010 at 08:49

Try Forte specialist injection cleaner c£14 for 400ml;if it does the trick for my local MOT station I`m sure it`s good enough for the rest of us :)

Shopping results for forte injection cleaner

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Edited by Avant on 03/10/2010 at 21:55

A big thank you for all your input and advice. Very helpful.

As it happens, a bout of 'man flu' meant I never got to do the filter and injection cleaner. I took it in on Monday and they slapped it on the computer, it showed the lambda had failed and when tested it was doing nothing!

£200 for a new one (there isn't a Bosch replacement for this model - so had to get the original part from Volvo!) and it sailed through the test with hardly a breath of CO.

Left it in for a full service and fingers crossed will have another 12 months super comfy motoring, might even take it up to 200k!

Thanks again, I'll be running the injection cleaner any way as it sounds like a good idea.

FF.