[mr tickle]

Originally Posted by Tannaton

As he said it needs to go on some Volvo or Volvo compatible gear.

These symptoms are a first for me - never ever heard of a [electronically managed] Volvo engine revving out of control, with the exception of diesel runaway when the turbo leaks oil into the inlet tract, but you would have a lot of smoke from the exhaust if that was the case.

Notice a throttle sensor error but I'd say that's unlikely the cause as Volvo cars have redundant sensors on the throttle - one digital and one analogue circuit. Almost aircraft levels of redundancy.

However in the absence of an obvious cause, you can't really rule anything out...

I'd disconnect the throttle sensor, i *think* the car should start but just tick over. I'd also try reading sensor values, which you should be able to do with a basic diagnostic, the MAF, APS, TPS and Brake pedal sensor - with the ignition on but engine not started.

And finally, don't buy any new parts until you've got a firm diagnosis, poke and hope substitution in the absence of diagnosis and/or experience will just empty your wallet on these cars. Spending £50-£80 to get it on proper gear will in 8 out of 10 cases tell you exactly what the problem is.

I think what he means is that when you start the car it will allow you to rev normally and up to the redline, it's when you allow the revs to drop to idle it then won't rev.