I have a 59 plate 1.6 TDCi Duratorq engine focus, owned from 2010 (9K) to now (115k) and serviced on time at a main dealer.

I'm getting P0299 code (underboost) whenever I floor the accelerator.

No problems if I take it easy.

I changed the fuel filter a few months back, after this code came up and it was fine for a while until now.

Yesterday I took the EGR valve off and cleaned it as there was a 'stuck EGR valve' code coming up. This now seems ok, but I am still getting 'Underboost'.

I cleaned the MAF and I've looked over all the induction pipes, checking for splits. None found.

I'd had a DPF sensor pipe leak but this is fixed now too.


Reading a lot of posts on the net, it seems that the 1.6 turbo's have a flaw and the bearings may be on they way out, due to the oil supply pipe filters getting blocked with gunge. At very expensive job to repair as the turbo needs replacing and the engine needs cleaning internally to get rid of any gunk.

Before going down that route, anything else worth checking?

The turbo actuator is moving up and down all time while on idle, it moves slowly up then jumps back and repeats.

The turbo seems to spin ok, it doesn't freewheel much if you give it a spin and there is a slight bit of play in the shaft which you can just feel when moving it.

I have a decent OBD scanner which can record nearly every sensor on the car, so I wondered if recording the MAP, MAF, RPM, fuel pressure, Throttle while driving and accelerating to get the fault up, would show me anything useful? Not sure where I'd find out what these should read on a 100% working car?

Any ideas?

Cheers!