Octavia mk vrs 2.0 tdi PD. Getting the dreaded p299 fault code. Currently experiencing low boost pressure. I am going through a process of elimination. I do have a query though if anybody can help. Fuel temp is a constant 125 degrees even on a cold start, I have fitted a new sensor but it still reads the same. I know the ecu looks at varies temperatures and calculates how much fuel to send into the turbo, all based on air density to produce a cleaner fuel burn. But if my ecu says the temp is high it will not be feeding enough fuel in. Does anybody have any ideas and what is the normal operating fuel temp.

26 minutes ago, Whoateallthepies said:

what is the normal operating fuel temp

In Cumbria I'd guess somewhere between 0 and 20C on a cold start almost any day.

I suspect the wiring to the sensor is damaged giving you a high reading, probably chaffing/corrosion going by age of vehicle.  Test resistance from sensor to wire termination.

 

Fuel is not sent to the turbo.

 

Move the turbo actuator by hand from stop to stop, it should move freely without binding and spring back positively to its at rest/low boost position.

 

If it feels rough/binds you probably have a worn/clogged VNT mechanism, try a fuel additive to remove the build up.

 

Check its operation with the engine running, at idle it should move to the max boost position.  If it doesn't move fully, either you have a poor vacuum for whatever reason, a sticky VNT mechanism or the actuator is bad.

 

 

 

 

 

Think I  have finally solved the P299 fault. I connected a smoke generator up and found a leak at the side of the manifold where the vacuum setting element connects. It turns out that the seal had gone not just by the element but on a couple of other chambers inside the manifold. Changed the manifold 10k miles ago and has never reappeared. Car runs nice and smooth through the gears.

Thanks for the follow-up.