Found this online iv had quite a few of the common faults mentioned thought it would b helpful to others especially if your buying a S3.
Or you can see how many you have had ... Lol
Audi S3 1.8T common faults/ buying check list
Hopefully it may be of use to have a list of common S3 faults in one place. Based on experience on my car that I’ve owned for 6 years and/or research through these forums. I've noticed a large number of these faults in the last couple of months hence I decided to write a list, feel free to add to it. Apologies for any inaccuracies in advance. Shocking how many common faults there are for an Audi…
My car is an Audi s3 1999 8L, APY engine (pre facelift) 87k, 11 years old
Solution Age Mileage
Plastic clips that run up and down on regulator are prone to fatigue causing window to malfunction and not close.
Replace with A6 metal clips 5 34k
Plastic impeller prone to failure causing overheating and damage to thermostat
Replaced with metal pump, replace thermostat if overheating occurs 7.5 59k
Concert Stereo volume
EPROM memory is ‘write only’ memory which fills up every time volume is changed. When EPROM is full, every time volume is adjusted it will go silent or full volume
Repaired by OE Electronics, Salisbury 7.7 62k
Backup battery in Alarm Siren
Siren battery stops holding charge which leads to car alarm going off. A sign is 3 beeps from the rear passenger side before siren continually sounds.
Remove or replace alarm siren. Some have repaired this unit. 7.7 62k
Heat shield for cat
Bolts holding heat shield rust and break off causing a rattling exhaust noise
Replace bolts 7.7 62k
Plastic collars break off. These collars butt up to the mounting bush. Part from Audi has been updated.
Replace entire ARB 8.7 73k
Track rods ends and wishbone bushes
Prone to wear out.
Wishbone bushes crack.
Replace part 8.7 73k
Roof rail corrosion
Sealant along weld line joining roof to quarter panel breaks down and allows water in and hence corrosion
Respray both sides covered by warranty if less than 12 years old and not neglected 9.7 80k
Brake Vacuum Hose
Vacuum pipe connecting brake servo to inlet manifold uses a hard plastic which cracks at joints from heat cycling
Replace part 10.7 86k
Rear springs corrode and then snap at the base
Replace part 10.7 86k
Lumpy cold running and low boost problems. Test by removing, pushing diaphragm up then placing finger over vacuum tube on top. Diaphragm should stay put else needs replacing
Replace with OEM P/N ending 710N 10.7 86k
Brake light switch on pedal
Prone to fail overtime. Throws a fault intermittent fault code and eventually brake lights stop working. Less common on facelift models
Replace part 10.7 86k
DIS dead pixels
DIS pixels fail overtime 5 34k
Glovebox lid hinges
Hinges snap over time
Replace glovebox lid. 9.7 80k
Rough running at idle, running rich, running lean, cold start problems, poor mpg
Test 1 - Disconnect MAF and default MAF values will be used. Engine will run better if MAF is faulty.
Test 2 - Log Block 002 using VAG COM. MAF values should be 0.8xengine BHP.
Reset ECU with MAF changes
Clean with electrical cleaner or replace MAF. Reset ECU. 10.8 87k
Rear wash wipe
Pump running but water not coming out of rear wash wipe
Check jet is not blocked and then check pipe joins through the car by running pump and looking for leaks. Joint under the bonnet LH side tends to be first to come apart. 4 26k
Common Faults not yet had:
Xenons pointing towards ground
Sensors on nearside suspension front or rear can fail, or motors within headlight. If it’s the motor normally only one light is affected
Replace sensor or headlight motor
Rust along lower door trims
Door panels rust behind lower trim
Some have claimed on warranty
Clutch pedal switch
Causes car to over rev when the clutch pedal is depressed
Plastic part of pedal prone to failure
Early models used Hitachi coil packs and few failures. Hitachi packs replaced by bosch part which is prone to failure
Venturi vacuum pump
Can clog up with oil from the oil breather (this might only be on A3)
Can be cleaned or replaced
Breather / vacuum pipes
Prone to failure overtime from heat cycling
Replace affected pipe
Clutch/ clutch slave cylinder & flywheel
Clutch slave cylinders can fail, leaking fluid over clutch.
Both slave cylinder and clutch require replacing if slave cylinder fails. If clutch goes maybe worth replacing slave cylinder at same time
Can fail with age or if waterpump impellers fail and engine overheats. Plastic impellers can travel round engine and get caught in thermostat preventing to open and close correctly. Temp gauge no longer sits bang on 90 deg. Coasting downhill tends to drop below 90.
Replace part. Ensure battery is disconnected as thermostat is directly behind live connection on alternator
Coolant Temperature Sensor
Early models used a black sensor which are prone to failure. Uprated part is green. Causes poor running. Temp gauge become erratic, check values on block 011.
Replace part. Open then close header tank to release pressure before changing.
Door sensor microswitches
Switches cause DIS to indicate door still open after it has been closed
Microswitches need realigning
Front Sus Top Mounts
Top mounts wear out causing knocking noise
Remove suspension, Replace part
Plastic outer of oil dipstick becomes brittle and cracks. Sometimes broken parts can fall into engine.
Oil sump pick up pipe
Pickup pipes can become blocked with grit like material. Thought to be worse on BAM engines or engines running longlife servicing.
Drain oil, remove sump, clean oil breather pipe or replace (£12), reinstall using audi sump sealant. 3 bolts particularly difficult to reach
Same problem as front although less common, collars within bushes snap at the ends and entire ARB has to be replaced. Some have found ARB needs replacing after rear springs have been renewed
Replace entire ARB
Coolant Level Sensor
Sensors can fail overtime and indicates low coolant on DIS. Cabling to the switch can come loose from plug
Clean sensor or replace. Replacement involves whole new header tank
Fuel Pump Relay
The fuel pump relay is located under the driver’s side kick panel. Remove the lower panels to gain access to the relay box. When the fuel pump relay goes remove the lower panels to gain access to the relay box. When the fuel pump relay goes bad it will trigger many fault codes with electrical shorts to ground. The fuel pump relay is also used to turn on the injectors, and will show injector short to ground failures. If you open your door you hear the pump kick on, if the pump no longer kicks on, and you experience these codes repeatedly, replace the fuel pump relay.