TDI offerings from VW and Audi are great examples of awesome technology brought to the masses.  TDI engines have great power and torque #s right out of the box and can deliver 50MPG for 300k+ miles with proper maintenance.

There are many popular modifications available to increase power and mileage, with some extreme examples approaching 300hp with only a slight decrease in economy (42mpg…)  All of this power and value packed into a common platform that has a huge aftermarket for suspension and appearance goodies means that you can have a cool, sporty car that also gets ridiculous mileage!

Here are some basic bits and pieces of information you should have when considering a TDI for your stable.


1Z/AHU – 1996~1999.5- Rotary Style Pump

ALH – 199.5~2004.5- Rotary Style Pump

BEW/BRM – 2004.5-2006 –AKA Pumpe Duse or “PD”

CBEA/CJAA-2009+ Common Rail “Clean Diesel”

There is a sticker on the timing belt cover that has the engine code and serial number.

For a4-platform cars with the ALH TDI engine, maintenance history should looks something like this:

10k, 30k, 50k, 70k, 90k miles: minor service
20k, 60k, 100k miles: medium service
40k, 80k miles: major service
2 years: replace brake fluid with DOT 4 brake fluid
Every 40k miles: timing belt change (ALH engine through 2001, old type belt and tensioner, automatic transmission)
Every 60k miles: timing belt change (ALH engine through 2001, old type belt and tensioner, manual transmission)
Every 80k miles: timing belt change (ALH engine 2002, new type belt and tensioner)
Every 100k miles: timing belt change (ALH engine 2003, new type belt and tensioner with larger roller; BEW engine 2004-2005)

The new timing belt for ALH engines began to be used late in the 2001 model year (ALH engine number 500,000 and higher); the longer change intervals began to be put in the maintenance checklists in 2002. The larger roller began to be used in 2003. Note that the new-style timing belt change also requires changing the tensioner and replacing some bolts (the bolts need to be removed to replace the belt; using new bolts is specified).
Some 2001 owner’s manuals had incorrect timing belt change intervals.  Manual Transmission models should have their belt changed every 60k.  Automatics should be done every 40k. This goes to 80k/100k once the new style belt and tensioner are installed in the early engine.

Using the correct oil is especially important for all diesels.  The 2004+ cars will experience cam lobe wear if the 505.01 oil is not used. Note that when looking at VW dealer receipts, the correct oil part numbers are:

1996-2003 TDI engines in the US: ZVW-352-540S (Castrol Syntec 5W-40, which meets VW 505.00) or G-052-167-A2 (Castrol TXT 505.01, which also meets VW 505.00 in addition to VW 505.01)

2004-2006 TDI engines in the US: G-052-167-A2 only (Castrol TXT 505.01, which meets VW 505.01) — any non-VW 505.01 rated oil will result in denial of engine warranty service, according to the owner’s manual

Inspect timing belt condition (and if you know what the old and new types look like, note what kind is in the engine).

Inspect brake pad wear. The wear limit for the a4 platform Golf and Jetta front and rear brake pads is 7mm, including the backing plate. Rear brake pads tend to wear out more quickly than front brake pads on these cars.

Use a scan tool to check any codes stored in the ECU. Note: if the car has an aftermarket radio, someone using a VW 1552 scan tool may be unwilling to scan the car. See http://www.ross-tech.com/vag-com/aftermarket-radio.html . Note: be careful about scanning the airbags, since the airbag controller may die in some cars. See http://www.ross-tech.com/vag-com/vw_issues.html .

Common Problems:

a4 platform cars with ALH TDI engine:

1998-2002: Window regulator clips may fail. There is a 7-year warranty extension available for repair.

All Years: Mass airflow sensor may fail. There is a 7 year or 70000 mile warranty available for repair on pre-2002 cars.

1998-2001: Relay 109 may fail. Shine a flashlight between the steering column and the lower trim panel to find a gray or black block with a “109” (or “601” — upside down) on it. The black ones are failure prone (but are not too expensive to replace with gray ones).

1998-2002: Door latch switch (usually driver’s) may fail. This may result in odd behavior of the interior lights, alarm, and buzzer for headlamps left on. Warranty replacements may have used a newer type of door latch that is quieter when locked or unlocked.

1999- Golf / Jetta: Glove box door hinges are failure prone.

1998-: Brake lamp switch may fail, causing the glow plug light in the dash to blink (even though the brake lamps may work). A recall was issued for some cars in April 2004, according to the NHTSA web site.

2001: Some cars had an ABS controller that can catch fire. There was a recall on it.

2000-2001 Golf / Jetta / Beetle: Some cars have an airbag controller that self-destructs if scanned with a scan tool. See http://www.ross-tech.com/vag-com/vw_issues.html .

2000-2002 Golf / Jetta: Some cars have a hazard switch that may fail. This is under recall campaign VX.