[Clare]

I have a 2002 1.9l tdi that had an oil change,new battery , fuel filter and egr valve changed. The code 1556 is coming up. I don't know where to search for help with negative pressure intake or exhaust. O'REILLY'S couldn't locate schematics for sensor etc. Where do I go from here? Has anybody had this issue? It has more power now and is getting 40mpg vs 33mpg.

 

[Thejarhead]

Your turbo is not working. Vacuum leak or plugged intake or leaking vacuum turbo actuator.

Here is the low power check list, go through it.

17964/P1556/005462 - Ross-Tech Wiki

wiki.ross-tech.com

Diagnosing and Fixing Limp mode for A4 1.9TDI [low power troubleshooting]

Diagnosing and Fixing Limp mode for A4 1.9TDI By Canadian Grizzly Read the entire post prior to jumping to conclusions. This is a general overview on how to diagnose and fix a A4 1.9TDI that goes into “limp” mode due to an overboost of the turbo. While I’m by no means an expert I’ve gleaned...

forums.tdiclub.com

 

[pinkembers]

That TDI club article is super helpful, for me, the N75 valve is almost always the first source of problems.