Audi A4, S4

since 2000 release

Repair and operation of the car

Diagnostics of malfunctions

The description of diagnostics of electronic control systems and diagnostic codes are provided in the Head of System of electric equipment of the engine.

In this Section the simplest scheme of clarification of the reasons of the malfunctions and refusals happening in knots and systems of the vehicle is offered. Refusals and their possible reasons are broken into groups on a sign of the relation to certain components or systems of the car as, for example the engine, the cooling system, etc., besides, in the text are given the references concerning these problems.

Remember that the successful completion of search of causes of defect is not the black magic available only to skilled professional mechanics at all, and is defined by a combination of a certain knowledge and patient, systematic approach to research of a problem. It is necessary to move always from simple to difficult, to bring each check to the logical end, and to try not to pass the obvious facts - everyone can forget to fill fuel in a fuel tank or to leave included in illuminants for night.

And at last, it is always necessary to try to make an accurate picture of development of malfunction and to take the corresponding steps for prevention of recurrence. If refusal of electric equipment happened for a cause of infringement of quality of contact, check a condition of all other contacts and electric sockets of system at the same time. If the same safety lock several times in a row continues to fuse, there is no sense in its further replacement - it is necessary to try to find out a cause of failure. Remember that failure of a minor component can be a sign of violation of functioning of more important knot or the whole system.

Engine

To define, whether the spark is developed, it is necessary to turn out candles, to insert into tips and separately to put to weight. Thus do not hold a tip or a cable of ignition with hands, and use well isolated nippers. Ask the assistant to start the engine. If the spark is absent, address to the Head of System of electric equipment of the engine.

Procedures of diagnostics of an electronic control system and codes of malfunctions are given in the Head of System of electric equipment of the engine.

Start of the engine

All engines

- RKPP: Tighten the parking brake, completely squeeze out a pedal of coupling and hold it. Establish a check point in neutral situation. The switched-off coupling facilitates start of the engine, especially at low external temperatures since thus there is no friction from a check point.

- Automatic transmission: Install the selector in situation "P" or "N". Press a pedal of a brake and hold it.

Do not include a starter more than 30 with continuously, otherwise the starter and cables overheat.

Petrol engine

• Turn the ignition key and include a starter, without giving thus gas. As soon as the engine starts working, release a key. If during 5 about the engine it is not started, press a pedal of gas a little and again repeat start. If the engine is not started or at once stops, repeat start with half the squeezed-out gas pedal and if still start with completely squeezed out gas pedal is required. At the hot engine slowly squeeze out a gas pedal during start.
• Surely at once begin the movement, only at a hard frost let's the engine get warm during 30 pages.
  
  

  The unsuccessful, following one after another attempts of start of the engine can do harm to the catalytic converter since not burned down gasoline gets to it and when heating blows up.

Diesel engine

If the fuel tank was completely emptied, process of start after gas station lasts more long (till 1 min.) since thus air from fuel system is removed.

- On the warm engine preheat is not required. Start the engine at once, without giving gas.

The engine is not turned in start attempts

• Corrosion of plugs of the battery takes place or weakened fastening of tips of wires on them. Check a condition of plugs and tips. Tighten terminal clips, if necessary remove corrosion traces.
• The battery is discharged or faulty. If tips of wires are found pure and reliably fixed on battery plugs, turn the ignition key in the situation ON, then include headlights and/or screenwashes. If this electric equipment does not function, the battery is discharged.
• Transmission it is inexact it is established in situation "P".
• Conducting in a chain of system of start is torn off or weakened fastening of wires on plugs. Check a condition of wires, plugs and electric sockets of the battery, traction relay of a starter and the lock of ignition.
• The gear wheel of a starter is jammed in a gear wreath of a driving disk. Try to turn the engine for a crankshaft pulley. At the first opportunity remove a starter and check a condition of a gear wheel and a gear wreath.
• The traction relay of a starter (The head of System of electric equipment of the engine) is faulty.
• The starter (The head of System of electric equipment of the engine) is faulty.
• The ignition lock is faulty.

The engine is turned, but not started

• Start is incorrectly made (Address to the materials given above).
• The engine immobilizator is faulty or is not disconnected.
• The safety lock is faulty:
  • Electric fuel pump;
  • Electronic system of injection.
• Concerning check of safety locks address to the Head Onboard electric equipment.
• Empty fuel tank or low-quality fuel is filled in.
• The air filter is strongly polluted. Leakages of vacuum in elements of air supply, malfunction in a control system of injection of fuel and ignition take place.
• The battery is discharged (the engine is turned too slowly). Check functioning of electric equipment (address to the previous Section).
• Korrodirovana terminal connections of the battery or were weakened by their fastening (address to the previous Section).
• The fuel pump is faulty, its safety lock fused or the pump relay is damaged. Check for hearing noise of operation of the pump at ignition inclusion (The head of the Power supply system, release and decrease in toxicity of the fulfilled gases).
• Components of system of ignition (The head of System of electric equipment of the engine) are damaged or excessively moistened.
• Spark plugs are worn-out or faulty or the candle gap (The head of System of electric equipment of the engine) is incorrectly exposed.
• Conducting of an electric contour of system of start is torn off or disconnected or weakened fastening of wires on plugs (address to the previous Section).
• Conducting of a contour of the coil of ignition is torn off or disconnected or weakened fastening of wires on coil plugs (The head of System of electric equipment of the engine).
• The safety lock of the control unit of the engine is damaged, is faulty any of sensors: The hall, the pulse sensor, the sensor of temperature of cooling liquid or the soaked-up air (The head of System of electric equipment of the engine).
• Too low pressure of a compression. Replace sealing laying of a head of cylinders. If necessary repair the engine.

Diesel engine

• Start is incorrectly made.
• The engine immobilizator is faulty.
• The safety lock is faulty:
  • Electric fuel pump;
  • Systems of preheat.
• The engine is not heated-up: proverteispravnost of functioning of the device of preheat.
• On the electromagnetic locking valve there is no tension. Connect to the switch the voltmeter or a sampler on a light-emitting diode. Include ignition. The light-emitting diode has to light up. Otherwise it is necessary to find break of an electrical wiring and to eliminate it.
• The electromagnetic locking valve is faulty. Check reliability of fastening of the electromagnetic switch, check contacts. Switch on and off ignition. In the switch click has to be distributed.
• Damage to the line of supply of fuel or air to lines takes place:
  • Pipelines or hoses are mechanically damaged or littered. Clear fuel pipelines and remove air from lines and the filter.
  • The fuel filter is littered. Replace the filtering element.
  • It is necessary to check the filter and pipelines for availability of ice or wax in the winter. Put the car in the heated garage, add to system of gasoline.
  • Ventilation of a tank or the mesh filter of a toplivozabornik is littered. Clean.