Fixing an Audi 99 A4 Quattro

This page is an effort to document the long repair process of an Audi 99 A4 Quattro 1.8L turbo.

Note: there are subpages listed on the left, and repeated here:

Pages from elsewhere on the site:

eBahn stupid errors

Where to get cheap Audi floormats

How to replace car side mirror (glass only)

Repairing a torn and painted Audi leather seat


I have received it from someone who had an engine coolant leak.

The crappy plastic coolant flange has split. And the engine was operated with a very low level of coolant.

I have checked the compression, and replaced the cooling flange. Replacing is not the easiest job, but can be done. Just make sure to not bend or damage the many wires, tubes, and hoses next to the flange.

Refilled coolant and washed the engine with foaming degreaser. This is something that might be best avoided. If you really want to clean the engine, then do not spray the foam on any electrical connectors, and do not spray in the air intake area. When washing off, connect the hose to the hot water, and do not use too much pressure. It will actually make more sense to only spray on the engine itself where black oil spots are. Do not attempt to spray the whole engine compartment if it is not oily. Another good thing to do is to clean the bottom of the engine compartment as well. This will also aid in detecting any future oil leaks (more visible on a clean bottom).

Replaced spark plugs. When I removed them, they were coated in oil (that got into the spark plug wells). This is the second time I'm afraid I had oil flow into the cylinders. Please e-mail me if you had this experience and if you know if this is bad for the engine, oxygen sensors, or catalytic converter.

Started the engine, on idle the RPMs go up and down (about 500 RPM every second). Several check engine codes:

Error codes

Many people online said it could be MAF electrical connection problem. So I disconnected the battery and the ECM, and probed the wires. BIG MISTAKE! The engine would start, but then immediately die in a second after I reconnected everything.

The new CE code was: Throttle Body.

Had someone come with a VAG and try to adapt the throttle body. It said "ERROR". Read the forums. Turns out, you need to reset the trouble code (in the engine section of VAG) before the throttle body can be adapted. This is also a good time to clean the throttle body (do not disconnect the electrical connector when you do so).

The car started.

Bought a new MAF on e-bay. Which was a mistake. Do not buy a MAF, or any other component for an Audi based solely on the check engine trouble code. Find someone local (use this link) with a VAG, a special interface to Audi and VW cars which shows much more information. A VAG IS REQUIRED WHEN ATTEMPTING TO TROUBLESHOOT OR REPAIR AN AUDI.

It will show actual real time values for MAF, oxygen sensor, and the like. Only if the oxygen sensor is zero and not changing should you buy a new sensor. Apparently, an apparent MAF problem may instead be an oxygen sensor problem, MAF wiring problem, or a vacuum leak. Do not buy a new MAF before you eliminate those possibilities.

Which brings us to the next question: can you save money by buying a standard/generic oxygen sensor? I have just did, and we will find out. But everyone I spoke to recommended against buying anything other than OEM Bosch oxygen sensor.

At this point, I am troubleshooting the idle issue, and tackling other problems instead.

The car was not well taken care of, and there were some cosmetic problems when I got it, including:

1) Torn leather seat. Fixed by sewing it together. It was ripped at one of the seams on the seating surface. Very noticeable. When stitching, make sure to stitch both leather pieces to the old seam (should have taken a picture). Then carefully glue over the seam with E6000. Repairing a torn and painted Audi leather seat

2) Damaged black plastic piece under the front bumper. Glued it back together. When gluing plastic, do not use brittle super glue or plastic epoxy. It might seem strong, but one future impact and it is going to fall apart. Instead use a specialized flexible plastic glue, or a flexible glue like E6000.

3) Leaking headlight washer

4) Missing headlight washer cap. This is impossible to find anywhere other than dealer, who wants an insane $25 for a 2x3 inch square piece of plastic.

5) Rusted and peeled lower door trim. This is available online, but for as much as $60. Once it is rusted, it expands, and cannot be glued back on the door or repaired.

6) Missing engine cover bolts (fasteners). These again are only available from the dealer, who wanted $12 for three plastic fasteners. Had to buy it. When putting them in, treat them carefully, and make sure the cover is aligned with the fastener holes. Do not use excessive force to push them in.

7) Missing radiator cap and lower bumper grille. Bought from RockAuto.

8) Missing wire harness/connector wire clip (the one that locks the connectors). Impossible to find anywhere, internet or dealer. Beg your dealer nicely to obtain it. These are not available for purchase separately (they do not have part numbers). E-mail me if you know where to buy some. Picture.

9) Many problems with the key. To start, there was just one remote key. No spare. If I lost it or locked it inside I WOULD BE SCREWED. So I decided to play it safe and trace (cut) a spare Audi key.

10) Several body scratches. The color code in the Audi is located in the trunk, next to the spare tire. Don't try to search the color code directly on the internet. Instead, head to places like this to choose by car make and model, and see if your color code is listed.

11) Problem with both mirrors. Replacement mirror costs too much, but just the replacement mirror itself (without the mirror body/case) can be obtained online. Instructions and large pictures on how to replace the side mirror (glass part).

12) Bought generic Wal-Mart floormats.

13) Bought an owner's manual on e-bay. Why? For the fuse diagram, and to find out all the features of the car (half of which you have no idea about).

14) Other missing parts: jack, lug nut wrench.

If you know where to obtain used or cheap jack, lug wrench, driver side lower door trim, headlight washer (passenger), headlight washer cap (passenger) then e-mail me.

Note: I may be able to help you with Audi questions if you contact me.

˅˅˅ Additional valuable information is available at one of the links below: ˅˅˅


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Page last modified 12-Apr-12 23:11:36 EDT

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