Hi, my 08 Vectra Auto has started going in to Limp Home Mode (Car with spanner light) whenever the car is in a DPF cycle and i put my foot down to kick the gearbox down a gear with very high revs, the car has only recently started doing this and never done it before.

As long as i dont force the gearbox to kickdown the car is fine and has no problems.

Kickdown works fine when not in a DPF Cycle and no other problems.

Car has 50k on the clock and full service history, gearbox oil is however now due for a change.

Any ideas on this one? Is it a gearbox issue or engine?

P.S: I have opcom but am not 100% on using it yet and dont know what im looking for so any help on using that to diagnose the problem would also be appreciated.