P0236 and P0235 Fixing these codes. - Alfa Romeo Forum
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P0236 and P0235 Fixing these codes.

Hi

Just wanted to add some of my experience with these fault codes

@ 2750rpm

Had a fault P0236 kept coming up. > over boosting.

1. P0236 Checked for fault > no vacuum at VNT actuator or solenoid/ fault fix was vacuum pipes had melted > replaced pipes.

Then another fault code reared its ugly head after the P0236 fix > P0235.

2. Changed the MAP sensor, (had a new spare) only after cleaning my old one up as it was gunky, and things smoothed out a little better, but still got the P0235 code and reduced acceleration @2750rpm and upwards engine light comes on.

3. Removed the Turbo and stripped it down to find the usual problem of sticking vanes, after cleaning out the rust and carbon and reassembling/refitting the turbo unit this has fixed the P0235 fault code as the VNT are no longer stuck open causing over boost.

So after a little bit of work () its running perfect now and the power is smooth going through the gears revving over 3000rpm and no more engine light coming on and the inevitable limp mode

So if you have this type of fault

1. Check vacuum is present at the VNT actuator and associated parts are working (slam panel solenoid).
2. Map sensor is clean from gunge clean and or replace with new one if fault still present after step 3.
3. VNT has free movement disconnect actuator and free movement of the turbo vane arm should be 10mm at least.

Cheers

Last edited by Alfa 156 JTD; 23-02-11 at 20:53.
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Was the turbo tricky to clean internally? Thats not something I've ever touched so was curious.

Thanks,

Keith
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Quote:
Originally Posted by gammakeith View Post
Was the turbo tricky to clean internally? Thats not something I've ever touched so was curious.

Thanks,

Keith
Cleaning the inside is easy so long as you don't use power tools and just scotch pads and or emery paper, lots of Wurth HHS2000, Wurth Rost Off, WD40 or similar release agent

If you have good tools (and not a mickey mouse set ) then the procedure is quite easy.

I have never had to use heat to remove bolts or separate the turbo casing.

Pay attention to where to hit the turbo bearing housing to separate the two halves, dont hit the aluminium parts.

This might help you.

From tdiclub.com

PDF repair file

http://www.megaupload.com/?d=93FZ92KB

And when it is all said and done this is how your VNT actuator rod will move!

http://pics.tdiclub.com/data/500/2006_0603_175432AB.AVI

Last edited by Alfa 156 JTD; 26-02-11 at 11:00.
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Thanks for the extra info. The PDF is a great guide. I'll add an actuator rod check to the list for the spring and if at all sticky do a preventative overhaul. Cheers again!!!!

Keith
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