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Audi S3 1.8T common faults/ buying check list

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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


Common Fault

Solution Age Mileage

Window Clips

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

Front ARBs

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

Rear springs corrode and then snap at the base

Replace part 10.7 86k

Diverter Valve

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

Replace switch

Clutch pedal

Plastic part of pedal prone to failure

Coil Packs

Early models used Hitachi coil packs and few failures. Hitachi packs replaced by bosch part which is prone to failure

Replace part

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

Oil dipstick

Plastic outer of oil dipstick becomes brittle and cracks. Sometimes broken parts can fall into engine.

Replace part

Ignition Barrel

Fail overtime

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

Rear ARBs

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.

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Additional faults I had on my 8L S3 (bought in September 2000, and px'ed in May 2003):

Yaw sensor

Failed in wet weather, causing ABS light to come on and ESP & ABS to be disabled.

Hazard switch

Failed, causing indicators to all flash unless held in with masking tape.

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Hi has anyone experienced steering problems. I've recently got loads of play in the steering, I've changed arms and track rod arms.

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Hi has anyone experienced steering problems. I've recently got loads of play in the steering, I've changed arms and track rod arms.

Recently had them changed or changed them your self? Was everything tightened correctly and wheels OK?

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