Code P1557 -- Is it a false code???

I have 135k on my 2001 jetta TDI. At about 2800-3100 rpm on acceleration my turbo falls flat on its face. Check engine light comes on for a short period. Code P1557 appears and is not defined. Stealer advised "turbo Overboost" and scratched their head. Had no idea what could cause this. They replaced the MAF and Boost Pressure Reg. (n75 Valve) at the tune of $648. Still have the problem. Took to a "real" mechanic and had the intake pulled/cleaned. Had timing belt replaced (again). Also cleaned turbo intake and had adjusted to manu spec. Still have problem. After continous driving (15-30 miles) check engine light resets. Turbo acts fine. (additional note: when turbo falls out, turning key off then back on while driving releases turbo back to normal operation.) Desperately wanting issue solved have been trying everything besides replacing turbo to correct. Have been told turbo operates fine and there is something else causing problem. I have been dealing with this issue since about 70k miles, and it is progressivly getting worse, now when stopping the engine shudders like its going to die out but doesnt. I was told but the stealer my rotors were warped and I replaced front brakes. This did not change a thing. I have had this vehicle to several different stealers. I think they are all morans!!! "Any Suggestions??????

You are having an overboost situation:the actuator rod could be rusty and sticking or the internal vnt mechanism is hanging up due to carbon build up and corrosion.Remove the turbo, replace it or take it apart and remove the carbon and corrosion .As for the shudder when stopping engine check to see if the anti shudder valve functions.

Check the vac system. If you look in this picture, you'll see a little plastic valve up by the firewall. Half is white, half is black. (black half goes to the passenger side). Anyway, I'm having a similar problem with a friends car. His intake is clogged too and I will be cleaning it in the next day or so. I replaced all his vac hoses as they were beat. Problem wasnt solved, so I looked further. I saw the valve and figured what the hell. I pulled it and tested it by blowing and sucking thru both sides. It allowed air to pass both ways. It shouldnt..... I poured a solvent into it and tapped the solvent out over and over again. Black gook stuff came out each time. In between each cleaning I blew compressed air thru it. When the black stuff coming out seemed diminished I sprayed wd40 thru it, again blowing it with compressed air after. This really cleaned it quite a bit. Once I was done, air would only pass thru one direction, as I believe it is designed. I would have just replaced the part, but unfortunately its priced quite high, Impex lists it (Part # 046 905 291A) at $64.10!!!!!!!!!!!!!!!!!!!

Anway, once it was fitted back to the car, (remember, black side to the passenger, white side towards the driver) the car seemed to respond much better. Though its still having problems and goes into limp mode, it takes much much much longer. Give cleaning that thing a try, it couldnt hurt.

Oh, also, my on my friends car his anti-shudder valve was dirty and the actuator was misaligned, so the flapper was partially closed all the time. The fact that the car wants to stall makes me think that it may be vac related.

do a search on n75 valve(the one mentioned above)
and vnt actuator or vnt. should yield plenty of info on this
problem.

i don't get the toilet roll pic??

i don't get the toilet roll pic??

Click to expand...

I am rennovating my bathroom and I'm looking for a porcelain TP holder thats recessed into the wall. I did a search online and this showed up. I just thought it was funny. Suicide resistant tp holder......

Thanks for the input man but as stated I have done all of this!

I've got the same problem going on too with the same code. Not fun. I will be changing all the hoses and cleaning the valves out. I have a N75 on the shelf waiting to be put in if the aformentioned attempts do not work. Who knows.

Good luck TFH
Dave