Audi A4 B7 - The most common problems and breakdowns

What are the most common Audi A4 breakdowns and how to fix them?

Audi A4 - ALL MODELS 
PROBLEM - Scraping sound from the front and / or rear brakes, with the pedal depressed or released.
CAUSE – Rock/debris between rear pads and brake disc, front and rear pads.
REPAIR – Remove the front wheels and front brake discs and remove foreign matter and/or debris. Repeat the process at the back.

Audi A4 - ALL MODELS  
PROBLEM - Noise from the power steering.
CAUSE - Power steering fluid below the MAX mark on the dipstick in cold conditions. Air in the power steering fluid.
REPAIR - Top up the power steering fluid to the MAX mark, and if the engine is 10 mm above the MAX mark.

Audi A4 - ALL MODELS 
PROBLEM - Startup error. Battery discharged. The fans continue to run after a maximum shutdown time of 12 minutes.
CAUSE - Water entering the engine control relay. Damaged wire to terminal 87 in engine compartment fuse box.
REPAIR - Check for damaged wiring in the fuse box/relay board in the engine compartment and repair the installation if necessary. Test engine control relay, replace if faulty.

Audi A4 - ALL MODELS 
PROBLEM - Glass and headlight washer system failure.
CAUSE - Fuse no. 37 (25A) burned out.
REPAIR - Remove fuse no. 37 and replace with 30A fuse. Repair the specification in the fuse box cover and instructions.

Audi A4 - ALL MODELS 
PROBLEM - The central brake light does not work. Rear window washer / wiper system error.
CAUSE - Electrical installations damaged by rear door / boot hinges.
REPAIR - Repair / replace parts of the electrical installation.

Audi A4 - ALL MODELS 
PROBLEM - Squeaking sound from the front suspension.
CAUSE - Dry joints of the lower shoulders of the front suspension.
REPAIR – Install new lower front shoulders.

Audi A4 - ALL MODELS 
PROBLEM – Squealing from the rear brakes under light braking.
CAUSE - Friction between brake lining and brake disc.
REPAIR - Install the modified rear brake linings.

Audi A4 - ALL MODELS 
PROBLEM - Malfunction Indicator Light (MIL) illuminates. Loss of engine power at higher rpm.
CAUSE – Engine control vacuum tubes damaged or cracked.
REPAIR - Check vacuum lines for damage and replace if necessary.

Audi A4 - ALL MODELS 
PROBLEM - Engine Malfunction Indicator Lamp (MIL) illuminates.
CAUSE - Software error engine computer (ECM).
REPAIR - Test components, electronics and mechanics (as needed) to eliminate other possible causes. If no error is found: Program again engine computer (ECM) with upgraded software.

Audi A4 - ALL MODELS 
PROBLEM - Poor performance or air conditioning system failure. The engine does not start. Fault in one or more electrical systems. The engine coolant fan is not running.
CAUSE – Open circuit/excessive resistance of electrical installations due to water ingress.
REPAIR – Test electrical and mechanical components (as appropriate) to eliminate other possible causes. If the error is not found: check the connection of the electrical wiring of the engine. Find the damaged wire and repair it with the electrical repair kit.

Audi A4 - MODELS WITH VIN CODE 8E4A140001 
PROBLEM - Bubbling sound from rear muffler when accelerating.
CAUSE - Accumulated condensation in the rear muffler.
FIX – Install a modified rear muffler.

Audi A4 - MODELS WITH VIN CODE 8E4A20896 
PROBLEM - Malfunction Indicator Light (MIL) Illuminated, Cranking Fault, Engine Misfire, Low Battery.
CAUSE - Faulty engine control relay (part no. 443 951 253 AA).
REPAIR - If there is a fault in the engine computer (ECM), replace the engine control relay.

Audi A4 - MODELS 2001-04 
PROBLEM - Headlight washer system error.
CAUSE – Insufficient permissible fuse load. Headlight washer pump defective.
REPAIR – Replace fuse F37 (20A/25A) in fuse box/relay board 1 with a 30A fuse. Replace the fuse load label under the fuse box cover with the corrected fuse load. Replace the headlight washer pump and install the protective cover.

Audi A4 - MODELS WITH WINE CODE 8H4K000446 
PROBLEM - Engine coolant fan motor does not operate. The engine overheats.
CAUSE - Faulty engine coolant fan motor control module.
REPAIR – Replace the engine coolant fan control module.

Audi A4 - PETROL ENGINE MODELS 
PROBLEM - Faulty idling and engine power drop.
CAUSE - Coil error on one cylinder.
REPAIR – Test the coil with an oscilloscope to confirm the fault. Install the new batch coil.

Audi A4 - MODELS FROM: 2005 - 2007 
PROBLEM - Engine Malfunction Indicator Lamp (MIL) illuminates. The engine pulls poorly.
CAUSE - Engine computer software (ECM) error.
REPAIR – Program the Engine Computer (ECM) with upgraded software.

Audi A4 - MODELS FROM: 2005 - 2007 
PROBLEM – The engine does not start or starts and then shuts off. Immobilizer on.
CAUSE - Immobilizer installation damaged by steering column.
REPAIR – Remove the steering column cover. Inspect the immobilizer installation for damage, repair as necessary. Secure the installation to prevent further damage.

Audi A4 - MODELS FROM: 2005 - 2007
PROBLEM - Airbag control indicator illuminates.
CAUSE - Lubricant or dirt in the SRS airbag connector under the front seat.
REPAIR - Clean the connector contacts. Clear the error memory.

Audi A4 - MODELS WITH AUTOMATIC TRANSMISSION 
PROBLEM - Malfunction Indicator Light (MIL) illuminates. Gear position indicator blinks.
CAUSE - Software error in Transmission Control Module (TCM).
REPAIR – Test electrical and mechanical components (as appropriate) to eliminate other possible causes. If no fault is found: Reprogram the transmission control module (TCM) with upgraded software.

Audi A4 - MODELS 2005 - 2006 
PROBLEM – Coolant is leaking from the pipe connecting the block to the cylinder head.
CAUSE - Defective O-ring at pipe joint.
REPAIR – Place a modified O-ring on the tube connecting the block. Tighten the pipe bolts to a torque of 10 Nm.

Audi A4 - 2007 MODELS 
PROBLEM - Sudden engine shutdown and inability to start.
CAUSE - Camshaft Position (CMP) sensor signal interference.
REPAIR - Replace the camshaft position (CMP) sensor. Tightening torque: 10 Nm. Inspect for a damaged camshaft position (CMP) sensor O-ring. Replace if necessary.

Audi A4 - MODELS 2005 - 2007
PROBLEM - Malfunction Indicator Light (MIL) illuminates. The engine pulls poorly.
CAUSE - Engine computer software (ECM) error.
REPAIR - Reprogram the engine computer (ECM) with the updated software.

Audi A4 - MODELS WITH ENGINE CODE BKP 
PROBLEM - The engine does not start.
CAUSE - Water enters the engine computer (ECM) due to an incorrectly installed protective panel under the windshield.
REPAIR – Replace the engine computer (ECM). Check that the protective plate under the windshield is correctly installed.

Audi A4 - MODELS 2.0 TDI 
PROBLEM - The engine does not start.
CAUSE - Internal short to one of the fuel injectors. Internal damage to the computer engine (ECM).
REPAIR – Test components, electronics and mechanics (as appropriate) to eliminate other possible causes. Test the fuel injectors and replace if necessary. Check engine computer (ECM), repair/replace as necessary.

Audi A4 - MODELS 2.0 TDI 
PROBLEM - A cold engine starts and stops hard. White smoke comes out of the exhaust.
CAUSE - Engine computer software (ECM) error.
REPAIR - Test electronics and mechanics components (as needed) to eliminate other possible causes. If no error is found: Reprogram the engine computer (ECM) with the upgraded software.

Audi A4 - MODELS WITH AIR CONDITIONING 
PROBLEM - Incorrect display of outside air temperature. The outside air temperature of the heater / air conditioner does not match the settings.
CAUSE - Poor connection between outside air temperature sensor and assembly connector. The electrical wiring of the outside air temperature sensor connector is not correctly installed.
REPAIR - Check the wiring harness connections of the outside air temperature sensor. Check and clean the contacts of the outdoor air temperature sensor multi-connector. If no error is found: Replace the outside air temperature sensor.

Audi A4 - MODELS WITH AIR CONDITIONING  
PROBLEM - The smell of mold when the fan is running. Water entry into the front legroom.
CAUSE - The air evaporator exhaust pipe is blocked by the sound insulation of the transmission. Accumulation of stagnant water.
REPAIR - Install a sponge insert between the A/C evaporator discharge tube and the transmission sound insulation. Replace the cabin filter if necessary. Disinfect the air conditioning system with a suitable agent.

Audi A4 - PETROL MODELS 3.2 2005 - 2006 
PROBLEM - After a cold start, the engine runs rough. Hesitation when accelerating when the engine is cold. The idle speed drops sharply and increases in reverse gear.
CAUSE - Engine computer software (ECM) error.
REPAIR – Test components, electronics and mechanics (as appropriate) to eliminate other possible causes. If no fault is found: Reprogram the engine computer (ECM) with upgraded software.

Audi A4 - ALL PETROL MODELS 
PROBLEM - Unusual noise from engine coolant pump area at idle.
CAUSE - Air in the cooling system.
REPAIR - Bleed the cooling system several times. Start the engine. If noise is still present: Replace the coolant pump.

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Mladen

Hi there, I am Mladen and I am an auto enthusiast. I started this blog years ago to help like minded people share information about latest cars, car servicing ideas, used car info, exotic cars, and auto technology. You will find helpful articles and videos on a wide variety of cars - Audi, Mercedes, Toyota, Porsche, Volvo, BMW and much more. Ping us if you have anything cool to share on latest cars or on how to make older cars more efficient, or just want to say hi!