Former VWDieselParts.com Forum

Low power and a code P1556. Says that the turbo pressure controller valve has deviated positive......or something like that, as best I can remember.

Anyone know what this means and what to do about it?

Thanks

You need further checks and preferably scanned with Vag/com. I assume your using a generic scanner since you gave a "P" code. Vag/com codes dont have "P's".


The VNT's have trouble sticking at high boost so when the computer notices it "failsafes". See <a href="http://forums.tdiclub.com/showpost.php? ... ostcount=1" target="_blank">This Thread</a>

There is a N75 solenoid that controls boost and it could have failed or the vacuum lines to it could be off or leaking.

And of course lets not forget about carbon clogged intake.

Note: Put your year/make/model in your signature!

2000 Jetta diesel. Yes, generic scanner

Thanks for the info. What is VNT?

That's the type of turbo.
It stands for Variable Nozzle Technology I think.... more modern and efficient than the old k24 or garret.

Hey Fats.....good to see ya. So you're still hanging around here. You still running "fat" in yours?

Yeah, the bowling ally called me this morning, seems they snowpiled their grease dumpster in and had cubes of oil pileing up around it. I grabbed 15 gallons today, out of about 50,... a small Rabbit load.
About a high of 10F today but the oil was still liquid when I pulled them out of the snow.... that's good oil
Might as well stockpile some, incase the Bushistas invades Iran, ha.
Oh, and I voted for a Republican at the caucus.

YOU VOTED REPUBLICAN!?!

Holy crap, the world is spinning backwards on it's axis. Actually it's not that big a stretch, you no doubt voted for Ron Paul if it was a Republican. I can see your anti-war agreement but can't see much else for you to like. I'm thinking Obama is most in line with how I perceive your views (how *I* perceive them).

I like a lot about Ron Paul, I consider myself a Libertarian first, a Republican second.

BTW, I think we found the problem with the turbo. There was a vacuum line that was rubbed thin. Not all the way through but I think thin enough to cause it to collapse. It's been fine since that was fixed.

Glad to hear you found the problem.
Naaa, Obama doesn't care about the constitution.... and won't stop looting us.

Sorry this is an old thread.

VAG Error Code: 17964
EOBD II Error Code: P1556

Fault Location:
Charge Pressure Control - Negative Deviation

Possible Cause:
Reduced power output.
Limp mode.

Boost Pressure too Low.
Hoses/Pipes incorrectly connected, disconnected or leaking.
Charger Pressure Control defective.
Variable Nozzle Turbo (VNT) nozzles stuck.
Solenoid Valve for Boost Pressure Control (N75) defective.

Possible Solutions:
Check Hoses/Pipes to/between Components.
Check Solenoid Valve for Boost Pressure Control (N75).
Check/Clean/Replace Charge Pressure Control.
Check/Clean mechanism for variable nozzles.


As taken from my EOBD II Fault Codes software which I might post on here.