To make your shopping experience a pleasant,  rewarding transaction it's important that the customer know the engine code for your TDI.

The following guide will help you learn the engine code for the TDI that you own.

1996- Passat- 1Z and AHU
1997-Passat- 1Z and AHU
1997- Jetta -1Z and AHU
1998-Jetta-1Z and AHU
1999(early) Jetta 1Z and AHU
Comment: These engines look nearly the same ( they are inter-changeable) but they do have important differences on internal components.
To verify your engine code (on any TDI) you can check the build placard located in the trunk near the spare tire. This placard will clearly state the engine code for your TDI.

The next generation of TDI   was the ALH engine.
1998 -2003 New Beetle ALH
1999.5-2003 Jetta ALH
1999.5-2003 Golf ALH

The TDI took the next advance with the advent of the Pump Duse or PD engine in 2004 ( US market).
2004-2006 New Beetle-BEW
2004-2006 Golf -BEW
2004-2005 A-4 Jetta-BEW
2004-2005 B5.5 Passat - BHW

In the later half of 2005 the new A-5 platform came to the US market.
2005-2006 A-5 Jetta-BRM

You now have an (condensed) over-view of the TDI engine codes
1Z, AHU, ALH, BEW, BHW, BRM

If you have any doubt then please check the build placard located in the general area of your spare tire.
 
Thank you.