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There are at least EDIT *NINE* things that can fail on your AAN (or ABY or ADU) (and 3B with some minor differences, as noted below) and leave you stranded at the side of the road, waiting for a tow truck. In no particular order, these include:
1. The G6 fuel pump, 8A0906091G, will fail with little or no warning. It might be fine in the morning and you stop a diner for lunch and the engine won't restart. You have a dead fuel pump.
Solution: Pre-emptively replace the 091G fuel pump if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new pump, sealed in a box in your trunk and this DIY pdf:
http://12v.org/urs/FuelPumpTestingan...dures_Rev2.pdf
More info: http://forums.quattroworld.com/s4s6/msgs/22623.phtml
2. The 034905161 G40 cam position sensor. This one is also potentially fatal. You might see a Check Engine Light (CEL) and get a 2113 blink code before it dies or it might be fine and then you stop and the engine won't start. Sometimes you can cool them down with some cold water poured down the back of the cam cover on the AAN/ABY/ADUs. IF that works, you are on borrowed time.
Solution: Pre-emptively replace the G40 cam position sensor if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement sensor from EFI Express (less than $20 without the bracket) and a printout of this DIY: https://plus.google.com/photos/10413...37779355510001
More info: http://forums.quattroworld.com/s4s6/msgs/22580.phtml
Note: 3Bs have a Hall sensor in the dizzy, they will fail, just maybe not as often as in an AAN/ABY/ADU. If so, I have this DIY for you:
http://12v.org/urs/ReplacementOfTheH...istributor.pdf The 3B plastic dizzy drive gear will also fail. Aftermarket metal replacements are available.
3. The coolant "T" at the back of the head that holds the temperature sensor that the climate control uses. This "T" gets brittle and will sometimes let go without warning. This will cause a massive loss of coolant which will often take the head out due to over heating.
Solution: Pre-emptively replace the "T" if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement "T" with you. OR, have something (copper pipe and clamps) that you can used to bypass the sensor (fine in the summer).
Here is the "T" between the head and fire wall. Look for the blue coolant temp sensor (not used by the ECU):
Here is the replacement part:
Photo courtesy of mannywdc
More info: http://forums.quattroworld.com/s4s6/msgs/22679.phtml
4. Turbo coolant return line. This is a real mofo if it goes because it lives under the intake manifold and is very difficult to get at. When it fails, you lose a lot of coolant, potentially, over heating the engine and warping the head. It is PN N0202621, as shown in the photo below.
Solution: re-emptively replace the hose if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement length of N0202621 hose with you. (Sold by the metre, share with your local UrS colleagues)
That other hose under the intake manifold will also fail but not as often as the turbo coolant return hose will. Same solution: Replace or carry a spare piece of hose.
5. After-run coolant pump. This pump comes on after you have stopped the car when the coolant temp is high. The plastic gets brittle and the nipples will break, dumping coolant.
Solution: Pre-emptively replace the pump, PN 034965561C, if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement or carry a piece of hose with copper fittings (as shown below) that you can use to bypass the pump until you get home.
The bypass trick:
Photo courtesy of swordfish.
More info:
http://forums.quattroworld.com/s4s6/msgs/21503.phtml
6. Serpentine Belt The AAN and ABY accessories, e.g. PS/PB pump, aircon, alternator, etc. are run off a serpentine belt. If the belt breaks, you have none of the above. If the broken belt doesn't take out the timing belt (it can and has), you can still drive the car (with some extra effort) but eventually the battery will go dead flat and you are done.
Solution: Pre-emptively replace the belt if the miles since the last replacement are high (e.g. 100K mi (160K km)) (A/C equipped, 054903137B,6 rib 21.36 X 1693MM or Non-A/C Serpentine belt (i.e. non-North American or A/C delete)= 054903137A, a 6 rib 21.36 X 1293MM) or carry one with you in your spares box. However, since the serpentine belt can take out the timing belt on its way out of the engine bay (killing the head), the pre-emptive solution is better. They aren't that expensive and take only a few minutes to change.
More info here: http://forums.quattroworld.com/s4s6/msgs/22579.phtml
Note: 3Bs have multiple accessory belts that should be checked and changed as necessary, particularly before a road trip away from your mechanic or shop or lock-up.
7. Coolant adapter 034121143E (aka "connecting socket") at the back of the head. The OE ones are plastic and get brittle and can crack dumping all your coolant. Disturbing it while changing the climate control "T" (item 3 above) will hasten its death.
Solution: Pre-emptively replace the adapter wth the plastic 034121143E one if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one or the metal Audi 100/200/5000 one (034121143) in your spares box in the boot.
Note: The 3Bs also have this coolant flange/adapter/socket, but it depends on the VIN of your car. Up to NA005118, the PN is 034121143. Starting at NA005119, it is 034121143E, like the AAN/ABY/ADU. No. 7 is also called a "connecting socket".
8. The oil pressure switch For the UrS4 AANs, the ABYs and ADUs, it is the white one, PN 056919081E, in the RS2 photo below (under the oil pressure gauge sender (or above it on some engines). This one happens less often but does happen and could kill your engine if you ignore the warning bells and lights. The plastic portion of the switch gets old and brittle and cracks allowing oil under pressure to squirt out in a messy nasty stream. It will release litres of oil in a short time. The threads are M10x1 (parallel not NPT) so not as common as the tapered VW version.
Solution: Pre-emptively replace the switch 056919081E (or 068919081 for the UrS6) if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one in your spares box in the trunk.
More info: http://forums.quattroworld.com/s4s6/msgs/96161.phtml
9. Ignition Switch They fail when the return spring force fatigues the plastic and the plastic cracks, releasing some of the spring force. This results in the key not returning to the RUN position from START. This can mean that portions of the devices on the load reduction circuit (activated during the START) are not powered. In some cases, the starter stays engaged even after the engine has started, killing the starter due to high RPM. You think you are fine until you go to restart the car after stopping on the road and nada, zip, crickets.
Solution: Pre-emptively replace the switch (4A0905849B) if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one in your spares box in the trunk. If your starter is dead, changing the switch won't help. You're done. (Even I wouldn't carry a spare starter (034911023X))
For C4 UrS cars (probably similar for the B3/B4 cars) follow this DIY for the Re and Re:
http://12v.org/urs/IgnitionSwitchReplacementDIY.pdf
**********************
There are more things but they don't fail as often or as fatally (you can still limp home or to a shop).
I will try link to or bump this post monthly (if I remember)
1. The G6 fuel pump, 8A0906091G, will fail with little or no warning. It might be fine in the morning and you stop a diner for lunch and the engine won't restart. You have a dead fuel pump.
Solution: Pre-emptively replace the 091G fuel pump if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new pump, sealed in a box in your trunk and this DIY pdf:
http://12v.org/urs/FuelPumpTestingan...dures_Rev2.pdf
More info: http://forums.quattroworld.com/s4s6/msgs/22623.phtml
2. The 034905161 G40 cam position sensor. This one is also potentially fatal. You might see a Check Engine Light (CEL) and get a 2113 blink code before it dies or it might be fine and then you stop and the engine won't start. Sometimes you can cool them down with some cold water poured down the back of the cam cover on the AAN/ABY/ADUs. IF that works, you are on borrowed time.
Solution: Pre-emptively replace the G40 cam position sensor if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement sensor from EFI Express (less than $20 without the bracket) and a printout of this DIY: https://plus.google.com/photos/10413...37779355510001
More info: http://forums.quattroworld.com/s4s6/msgs/22580.phtml
Note: 3Bs have a Hall sensor in the dizzy, they will fail, just maybe not as often as in an AAN/ABY/ADU. If so, I have this DIY for you:
http://12v.org/urs/ReplacementOfTheH...istributor.pdf The 3B plastic dizzy drive gear will also fail. Aftermarket metal replacements are available.
3. The coolant "T" at the back of the head that holds the temperature sensor that the climate control uses. This "T" gets brittle and will sometimes let go without warning. This will cause a massive loss of coolant which will often take the head out due to over heating.
Solution: Pre-emptively replace the "T" if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement "T" with you. OR, have something (copper pipe and clamps) that you can used to bypass the sensor (fine in the summer).
Here is the "T" between the head and fire wall. Look for the blue coolant temp sensor (not used by the ECU):
Here is the replacement part:
Photo courtesy of mannywdc
More info: http://forums.quattroworld.com/s4s6/msgs/22679.phtml
4. Turbo coolant return line. This is a real mofo if it goes because it lives under the intake manifold and is very difficult to get at. When it fails, you lose a lot of coolant, potentially, over heating the engine and warping the head. It is PN N0202621, as shown in the photo below.
Solution: re-emptively replace the hose if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement length of N0202621 hose with you. (Sold by the metre, share with your local UrS colleagues)
That other hose under the intake manifold will also fail but not as often as the turbo coolant return hose will. Same solution: Replace or carry a spare piece of hose.
5. After-run coolant pump. This pump comes on after you have stopped the car when the coolant temp is high. The plastic gets brittle and the nipples will break, dumping coolant.
Solution: Pre-emptively replace the pump, PN 034965561C, if the miles since the last replacement are high (e.g. 100K mi (160K km)) or carry a replacement or carry a piece of hose with copper fittings (as shown below) that you can use to bypass the pump until you get home.
The bypass trick:
Photo courtesy of swordfish.
More info:
http://forums.quattroworld.com/s4s6/msgs/21503.phtml
6. Serpentine Belt The AAN and ABY accessories, e.g. PS/PB pump, aircon, alternator, etc. are run off a serpentine belt. If the belt breaks, you have none of the above. If the broken belt doesn't take out the timing belt (it can and has), you can still drive the car (with some extra effort) but eventually the battery will go dead flat and you are done.
Solution: Pre-emptively replace the belt if the miles since the last replacement are high (e.g. 100K mi (160K km)) (A/C equipped, 054903137B,6 rib 21.36 X 1693MM or Non-A/C Serpentine belt (i.e. non-North American or A/C delete)= 054903137A, a 6 rib 21.36 X 1293MM) or carry one with you in your spares box. However, since the serpentine belt can take out the timing belt on its way out of the engine bay (killing the head), the pre-emptive solution is better. They aren't that expensive and take only a few minutes to change.
More info here: http://forums.quattroworld.com/s4s6/msgs/22579.phtml
Note: 3Bs have multiple accessory belts that should be checked and changed as necessary, particularly before a road trip away from your mechanic or shop or lock-up.
7. Coolant adapter 034121143E (aka "connecting socket") at the back of the head. The OE ones are plastic and get brittle and can crack dumping all your coolant. Disturbing it while changing the climate control "T" (item 3 above) will hasten its death.
Solution: Pre-emptively replace the adapter wth the plastic 034121143E one if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one or the metal Audi 100/200/5000 one (034121143) in your spares box in the boot.
Note: The 3Bs also have this coolant flange/adapter/socket, but it depends on the VIN of your car. Up to NA005118, the PN is 034121143. Starting at NA005119, it is 034121143E, like the AAN/ABY/ADU. No. 7 is also called a "connecting socket".
8. The oil pressure switch For the UrS4 AANs, the ABYs and ADUs, it is the white one, PN 056919081E, in the RS2 photo below (under the oil pressure gauge sender (or above it on some engines). This one happens less often but does happen and could kill your engine if you ignore the warning bells and lights. The plastic portion of the switch gets old and brittle and cracks allowing oil under pressure to squirt out in a messy nasty stream. It will release litres of oil in a short time. The threads are M10x1 (parallel not NPT) so not as common as the tapered VW version.
Solution: Pre-emptively replace the switch 056919081E (or 068919081 for the UrS6) if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one in your spares box in the trunk.
More info: http://forums.quattroworld.com/s4s6/msgs/96161.phtml
9. Ignition Switch They fail when the return spring force fatigues the plastic and the plastic cracks, releasing some of the spring force. This results in the key not returning to the RUN position from START. This can mean that portions of the devices on the load reduction circuit (activated during the START) are not powered. In some cases, the starter stays engaged even after the engine has started, killing the starter due to high RPM. You think you are fine until you go to restart the car after stopping on the road and nada, zip, crickets.
Solution: Pre-emptively replace the switch (4A0905849B) if the miles since the last replacement are high (e.g. 100K mi (160K km)) OR carry a new one in your spares box in the trunk. If your starter is dead, changing the switch won't help. You're done. (Even I wouldn't carry a spare starter (034911023X))
For C4 UrS cars (probably similar for the B3/B4 cars) follow this DIY for the Re and Re:
http://12v.org/urs/IgnitionSwitchReplacementDIY.pdf
**********************
There are more things but they don't fail as often or as fatally (you can still limp home or to a shop).
I will try link to or bump this post monthly (if I remember)
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