P0034

[tda1610]

Good afternoon all, I apologise if there is an answer already out there somewhere for this problem but I can't find it

I have a 2.0 turbo Vectra on a 54 plate which has been feeling under powered lately and last week the spanner light came on while driving. The code that came up with the flash test was P0034. After a little Google session I know this is Turbocharger Bypass Valve Control Circuit Low but what does that mean in layman's terms.

I'm generally up for most jobs and don't mind getting my hands dirty but could do with a few pointers if you don't mind chaps. Anything to keep it away from the fleecing dealer prices lol

[jonnyaykroyd]

A read of this thread on another forum may give you some clues:

http://www.saabcentral.com/forums/sh...d.php?t=134576

Turbocharger Bypass Valve Control Circuit Low - "Low" as in low voltage read by ecu on solenoid position sensor. I'm not sure where this is on the 2.0, but could be a short to ground on the wiring, or it might be a leak on a vacuum line?

[jonnyaykroyd]

Also try googling other related boost DTCs for possible leads such as P0033. Most are saab but is the 2.0 a similar engine in the:

http://www.saabcentral.com/forums/sh...d.php?t=118513
http://www.saabcentral.com/forums/sh...ypass+plumbing
http://www.saabscene.com/forum/threa...e-Losing-Boost

The only P0034 threads I've seen for the saab 2.0 though are electrical though, like connector not fully plugged in.

[jonnyaykroyd]

One final thought....I have a diesel so I don't pretend to know an awful lot about the 2.0T, but I've just been reading a bit of background info on how the boost works on the petrol turbo.

The diesel I have has a variable geometry turbo (powered by the vacuum pump and actuated by a computer controlled "boost control solenoid") and so it doesn't have/need a waste gate.

The petrol turbo has a Bypass Valve on the turbo itself which needs to be closed to allow boost to build (what your NOT getting) and then open when you let off the throttle in order to prevent a shockwave of air hitting the throttle plate as it closes. When you let off the throttle after accelerating the valve needs to open which essentially equalizes the pressure on both sides of the turbo. All this is controlled by PCV (positive crank case ventilation) and vacuum (from the manifold). So PCV keeps the bypass valve closed allowing boost to build, then if you let off the throttle the computer operates a solenoid controlled valve which switches the PCV to vacuum opening the bypass valve (waste gate).

So somewhere there will be a solenoid controlled valve (remote from the turbo) with a PCV going to it, a vacuum line going to it, the switched PCV/vacuum line to the turbo and an electrical connector. This valve may be stuck open, because the solenoid is stuck or the solenoid might have a wiring issue.

If no one else can help more, i'll look on TIS later for a little more info.

[vectra ste]

i found this thread maybe related

http://www.vectra-c.com/forum/showth...highlight=0034

[tda1610]

Cheers guys, is the bypass valve the thing bolted onto the turbo with a long rod which I think is connected to a flap inside the turbo then goes to a little saucer shaped component with a vacuum hose attached to it?