P0234 turbo overboost?

karter5

Member
Joined
Apr 6, 2010
Location
montreal
TDI
mkIV
I recently got the CEL for P0234 turbo overboost and have been driving with it for a couple weeks now. The car is a 2001 jetta tdi with 240xxx. Im suspecting its a vacuum leak ( hopefully ) and I've already checked the intake/snow screen and everything's fine, the air filter was changed about a month ago. Now I don't have a vacuum gauge really to check the lines but the cloth on some of the lines have been chaffed passed the cloth lining, could that be the cause and I should just go ahead and change them?
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
I would, it's pretty cheap to buy anyway and it certainly wont hurt.:)
 

JASONP

Top Post Dawg
Joined
Feb 24, 2008
Location
Guelph
TDI
2015 Golf TDI Comfortline 6spd
when in doubt, swap it out...as stated vac line is cheap I believe it's 5mm ID about 1mtr will do
next time use larger pics ;)
 

karter5

Member
Joined
Apr 6, 2010
Location
montreal
TDI
mkIV
hmmm as I was going to buy to vacuum line I noticed the check engine light hadn't come on and there is normal power again... but now it sounds like my belt is slipping :confused: . After multiple engine starts and continuous driving the check engine continues to stay off.
 

karter5

Member
Joined
Apr 6, 2010
Location
montreal
TDI
mkIV
sooo with all the VNT talk I decided to check it out. It seemed to move pretty freely from when I was checking under the hood, but decided what the heck and jacked it up to get a better look at it.....

:eek: I think it needs changing, amirite? ...lol.. but what confuses me if it was this bad how the heck was it intermittent :confused: . Rust is a common occurrence since I live in montreal. Any suggestions of where I could get this part for cheap? I read elsewhere that stealerships dont sell the part by itself.
 

karter5

Member
Joined
Apr 6, 2010
Location
montreal
TDI
mkIV
Soooooo I changed the VNT actuator and the car went back to being normal after about 3 restarts.. until today. The car now has a P1556 code, after a quick lookup it seemed the most common thing was a MAF sensor but I had changed it about a month ago. Could a badly adjusted actuator cause this?
 

Nutsnbolts

Vendor , w/Business number
Joined
Nov 1, 2001
Location
Weare, NH
TDI
2000 Jetta, Silver Arrow
That means that you now have the opposite problem- the turbo isn't boosting enough. So, take a look at the vacuum line that goes down to the actuator, and make sure that it is getting a little vacuum when the engine is running. If not, then the N75 valve might be stuck and need a cleaning, which is very likely given the condition of the previous actuator. It would be advisable to remove the vacuum line from the actuator and the N75 and blow some compressed air through it to make sure that here is no rust clogging things up. Also, put a vacuum pump on the actuator and make sure that it begins to move at 5-7inches of vacuum.

-Rich
 
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