Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSAUDI2004A4 BASE, 4D SEDAN, 3.0 TREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 9 (1.8L - MULTIPORT FUEL INJECTION (MFI), ENGINE CODE(S): AMB)
2004 Audi A4 Base, 4D Sedan, 3.0 T
Section 9 (1.8L - MULTIPORT Fuel Injection (MFI), Engine Code(S): AMB)
2004 Audi A4 Base, 4D Sedan, 3.0 TSECTION Section 9 (1.8L - MULTIPORT Fuel Injection (MFI), Engine Code(S): AMB)
WARNING: This page is about a different variant/trim than selected.
- Multiport Fuel Injection (MFI)
- Motronic injection system, servicing
- Safety precautions
- Rules for cleanliness
- Technical data
- Component locations, overview
- Notes
- Location
- Location of Fuel Pump (FP) Relay -J17-
- Location of Brake Light Switch -F- and Brake Vacuum Vent Valve Switch -F47-, Clutch Vacuum Vent Valve Switch -F36-
- Location of Throttle Position (TP) Sensor 1 -G79- and Throttle Position (TP) Sensor 2 -G185-
- Location of Engine Control Module (ECM) in electronics box (plenum chamber)
- Component locations in electronics box (plenum chamber)
- Location of Secondary Air Injection (AIR) Solenoid Valve -N112- and Recirculating valve for turbocharger -N249-
- Location of Charge Air Pressure Sensor -G31-
- Electrical testing using VAG1598/31 test box
- Procedure after interruption of voltage supply
- Engine Control Module (ECM) (without metal anti-theft housing), replacing
- Engine Control Module (ECM) (with metal anti-theft housing), replacing
- Idle speed (RPM), checking
- System pressure, fuel pressure regulator and residual pressure, checking
- Fuel injectors, checking
- Fuel rail with injectors, disassembling and assembling
- Fuel injectors, removing and installing
- Injection quantity, proper seal and spray pattern of fuel injectors, checking
- Fuel Pump (FP) Relay -J17- and relay activation, checking
- Mass Air Flow (MAF) sensor -G70-, checking
- Intake air system for leaks (unmetered air), checking
- Fuel system, bleeding
- Oxygen sensor system
- Oxygen Sensor (O2S) and Oxygen Sensor control before catalytic converter, checking
- Special tools and workshop equipment required
- Test requirements:
- Test sequence
- Checking Oxygen Sensor (O2S) adaptation values and Oxygen Sensor (O2S) control
- Evaluating display group 032 (below specified range)
- Evaluating display group 032 (above specified range)
- Evaluating display group 033
- Checking basic voltage
- Checking Oxygen Sensor (O2S) wiring
- Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor (O2S) heating -Z19- for oxygen sensor before Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor (O2S) and Oxygen Sensor control before Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor control after Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor (O2S) heating -Z29- for Oxygen Sensor after Three Way Catalytic Converter (TWC), checking
- Oxygen Sensor (O2S), removing and installing
- Oxygen Sensor (O2S) and Oxygen Sensor control before catalytic converter, checking
- Fuel tank ventilation system, checking
- Electronic power control (EPC) system, checking
- EPC system function
- Electronic Power Control (EPC) Warning Lamp -K132- in instrument cluster
- Electronic Power Control (EPC) Warning Lamp -K132-, checking
- Throttle Valve Control Module -J338-, checking
- Throttle Valve Control Module -J338-, adapting
- Throttle valve, checking for soiling
- Throttle valve control module, cleaning
- Angle sensors for throttle drive -G187- and -G188-, checking
- Throttle Position (TP) sensor 1 -G79- and Throttle Position sensor 2 -G185-, checking
- Kick-down function, adapting
- Brake Light Switch -F- and Brake Pedal Switch -F47-
- Clutch Vacuum Vent Valve Switch -F36-, checking
- Cruise Control System (CCS) switch -E45-, testing
- Additional signals, checking
- Special tools and workshop equipment required
- Engine speed (RPM) signal, checking
- Crash signal, checking
- Data exchange, Motronic / ABS (CAN-bus), checking
- Notes
- Checking the bus system
- The following systematic procedure is useful for troubleshooting if three or more control modules are communicating via a "two-line bus system":
- If you cannot determine a cause for the DTC "Powertrain databus malfunction," check whether the DTC is caused by one of the control modules
- Vacuum Hose Diagram(S)
- Motronic injection system, servicing
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.