P0234 Engine overboost Condition

**potnoodle** · 06-09-2008,09:48 PM

Hi Guys, Just bought a Mk5 140 tdi, no lights on when i got it and it drives around town superb loads of boost from the turbo and will rev all the way up.
I get it on the motorway and try to accelerate next thing you know about 60-75 mph the car goes into limp mode. I have plugged in a cheap code reader and I am getting the P0234 Engine Overboost Condition code.
I have done a ton of reading on here and the other gti forum regarding cleaning the Inlet Guide vanes in the turbo.
I am just after a bit of advice regarding this, before I go whipping my turbo off and giving it a clean.
is there any other faults that could cause these symptoms, ie put the turbo into an overboost position other than sticky IGV's?

Thanks Dave.

**Crasher** · 06-09-2008,10:40 PM

If the turbo is wheezing and whining, it usually needs replacing, this is a massive problem on the BKD engine. There is s spray cleaning system available from Inotec that allows the vanes to be cleaned without removing the turbo, if this fails it is new turbo time.

**potnoodle** · 06-09-2008,10:52 PM

Cheers for the quick reply crasher, I will have a look into that spray cleaning solution now.
BTW is this the only cause of the Engine overboost condition? or could it be a dodgy sensor?

**potnoodle** · 06-09-2008,10:57 PM

Just tried googling Inotec, to try and find a lead on this cleaning solution but to no avail, anything else that could point me in the right direction please crasher? Cheers for your time.

**Crasher** · 06-09-2008,11:16 PM

I can supply by mail order but not sure of the price until Monday when I can look on the works system.

**potnoodle** · 06-09-2008,11:29 PM

Crasher , Cheers. I will PM you my mobile, give me a text or leave a message on my phone( phones not allowed in work) and I will call you back during business hours and get it ordered. Thanks for your help.

**potnoodle** · 13-09-2008,06:45 PM

Update: Got the car up on ramps today and did a visual inspection of hoses , all seemed fine, worked the vanes by hand and didn't notice any sticking or noises, so took off the pipe with the MAP sensor fitted to it and what looks like oil started dripping out, cleaned the pipe, run a coule of kettles of boiling water over the map sensor refitted it and put the lot back together, took it for a very hard driving session on the motorway, and now can not get it to fail into limp mode now. Happy with the result, not so happy with oil being in the pipe between the cooler and inlet manifold and covering the MAP sensor. checked oil when I got home and it is about a litre overfull, going to drain a bit tomorrow, but now need to find out if this is the reason for the pipes having oil in or is this normal?
Checked service history and oil was changed at VW dealers 700 miles ago.

**Crasher** · 13-09-2008,07:16 PM

Oil in the pipes is completely normal and nothing to worry about. Some comes out of the turbo and some from the crankcase breather.

**potnoodle** · 13-09-2008,07:31 PM

Cheers Crasher, thats put my mind at ease.

**JohnVR** · 17-09-2008,10:14 PM

There is a fault with some of the 2.0 TDi's where the wiring from the boost sensor to the ECU has high resistance. To fix this we fit an adapter loom and clean all earth points along the N/S. Check the earth points to see if corroded.