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Discussion Starter #1
Turbo stops working and check engine light comes on. Turning car off and back on again "fixes" it. From what I've read so far, this sounds like "Limp Mode." It has been slowly becoming more and more frequent over the past few months from weeks at first to hours now.

Took it in for repair and had the "pressure converter valve" (probably the N75 referred to in other posts) and the MAF replaced. Mechanic claimed it was fixed, but he must not have found a big enough hill for the test drive, as the problem reappeared the next day.

Other info on the car: Previous owner warned us of the VNT actuator sticking when his wife drove the car. As an aggressive driver, I did not have any problems with the turbo for over a year. Still we should probably check this out.

It's got a diesel geek race pipe and an updated chip tuned for the race pipe.

Mechanic is the best VW guy for 30 miles, but I probably just wasted money on unnecessary parts. Got a buddy who is not a mechanic, but he has worked on his own TDI and is good with hoses. Also we plan to get the basic codes from the local parts store.
 

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Discussion Starter #3
Here's the code:
17964/P1556 - Charge Pressure Control: Negative Deviation

Possible Symptoms

* Reduced power output
* Limp mode

Possible Causes

* Boost Pressure too Low
* Hoses/Pipes incorrect connected, disconnected or leaking
* Charger Pressure Control defective
o VNT (variable nozzle turbo): 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
o Check / Clean mechanism for variable nozzles
 

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I have to add: I had the exact same problem with my TDI 2002. I just recently opened the intake manifold by the EGR valve and discovered a real mess. After cleaning this out I have untold boost! This seems to have fixed my limpmode and boost issues that I was having as I have hard lined it, run it up hills at full and done everything I can to make it fail but it just keeps going. Dunno if anyone has already mentioned this as I didn't notice it in your "have checked" list and its really easy to check. I should mention that I did get the "Over boost" code also before I found this issue.

Regards
 

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Discussion Starter #6
CCBB, thanks for the tip, looks like a helpful link. Looking at hoses now ...

Dutchviking, indeed I think that soot in and around the EGR valve is a common cause of limp mode. The previous owner of my car already dealt with this by installing a race pipe, and therefore I'm confident it's not my EGR.

According to Diesel Geek:
The Dieselgeek Race Pipe increases air flow into the ALH engine and eliminates intake manifold soot build up forever. This device replaces EGR valve on ALH engines used in mid-1999 through 2003 Golf and Jetta TDI and 1998-2003 New Beetle TDI. A solid 3 hp increase has been shown on dyno runs above 3000 rpm. Some have reported less smoke and a freer revving engine as well while using the Dieselgeek Race Pipe. It's also a beautiful part to compliment any engine bay.

Obviously from a biased source, but it's an interesting solution to all of our EGR problems. :)
 

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Ah ha! That comes from not having a clue what a race pipe is. Thank you for the info!:bowdown

Good luck with it!

Cheers,
Rick
 

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2003 Jetta losing power

I have the same problem with my 2003 Jetta, thanks for the info I will also check engine codes and look over all of the hoses.
 
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