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2004 BEW Limp Mode Boost Issue

26012 Views 12 Replies 6 Participants Last post by  Davidloc
Hi There,

I have a 2004 Jetta Wagon TDI with the BEW motor. The car has been going into limp mode nearly every day especially on very cold mornings while going up hill. I unfortunately I did not copy down the code that was thrown but it was related to an overboost condition.

***Start Edit
16618 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
P0234 - 000 - -

I took car out for a test drive an was able to make it go into limp mode again and reproduce the fault code above. I also checked the MAF via VCDS and it seems to be fine as the actual tracks the requested up to ~800 or so and back again.

***End Edit.

Today I replaced all vacuum lines (one at a time), the N75 valve, and the check valve. By inspection the old check valve was broken (i.e. air flow in both directions = bad). I saw some minor wear on the vacuum lines but nothing special to note. I can freely move the actuator with my finger and have run the output test to verify that N75 is indeed moving the actuator under vacuum.

However, I am not convinced that the car is fixed. Please see that attached image of the VCDS scope screen. This plot is the result of revving the engine while in the driveway. The specified boost and the actual boost do not track as I think they should (per the 1000q faq). As you can see the actual is significantly higher than the requested.

Any ideas where to check next (MAP sensor maybe)? I would really appreciate any help that could be provided. I have searched the forums and faqs for weeks which led me to replace the vacumm system parts. Now it is time to ask for help directly.



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Defective BEW VNT Servos

I agree with captc, it is a shame that that VW won't sell a replacement actuator as a direct bolt on. I guess Planned Obsolescence is still the Big Business game plan. I’m sorry but you can’t sell me a new VW one if you can’t or won’t fix your old one. This is my second turbo that has failed with a faulty VNT actuator. This is also my second and last VW TDi. I will make sure that I let everyone know what a poor product VW manufactures. They should have pulled out of the American market in the late seventies when they threatened to do so. The Rabbit almost killed VW in the US then, and the Golf is nothing more than a Rabbit in disguise. It is the same poor quality different label. Renault pulled their junk out of the US market as did Citroen, and we didn’t miss them. I guess the fond memories of my 64 Beetle will be clouded with the memories of rusted out towers of my 97 Jetta and failed turbos of my 04 Golf. Anyone want to know how I feel about my E36 convertible, the other piece of German Junk I own? BTW I was born in Germany.
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