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.
Notes
Retrieving Diagnostic Trouble Codes: Notes β 1994 Audi S4 Service Manual : Notes With (VAG 1551)/1 adaptor connected to (VAG 1551) scan tool. Connect (VAG 1551) scan tool or generic scan tool to Data Link Connector (DLC). See CONNECTING SCAN TOOL (VAG 1551) under SELF-DIAGNOSTIC SYSTEM. Turn ignition on, start engine and let it idle. If engine will not start, operate starter for at least 5 seconds. Leave ignition switched ON. Operate (VAG 1551) scan tool according to display: Press button -1- to select "RAPID DATA TRANSFER" operating mode. Display will read - "RAPID DATA TRANSFER" "INSERT ADDRESS WORD XX". Press buttons -0- and -1- to enter "Engine Electronics" address word 01. Display will read - "RAPID DATA TRANSFER" "01-ENGINE ELECTRONICS". Press -Q- button to confirm input. Display will read - "RAPID DATA TRANSFER" "SCAN TOOL SENDS ADDRESS WORD 01". If display appears as shown - "RAPID DATA TRANSFER" "CONTROL MODULE DOES NOT ANSWER". Press HELP button to print list of possible malfunctions. If "CONTROL MODULE DOES NOT ANSWER" is still displayed after repairing possible malfunction, check white DLC wiring. Check voltage supply to the Motronic Engine Control Module (ECM). See SYSTEM & COMPONENT TESTING - S4 article. If Diagnostic Trouble Code (DTC) 65535 is displayed, ECM is malfunctioning. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION. After repairing possible malfunction: Again press buttons -0-and-1- to enter "ENGINE ELECTRONICS" address word 01. Press -Q- button to confirm input. If one of the following displays appears as shown: Press HELP button to print list of possible malfunctions. "RAPID DATA TRANSFER" "L WIRE NOT SWITCHING TO GROUND" "RAPID DATA TRANSFER" "L WIRE NOT SWITCHING TO B+" "RAPID DATA TRANSFER" "K WIRE NOT SWITCHING TO GROUND" "RAPID DATA TRANSFER" "K WIRE NOT SWITCHING TO B+" After repairing possible malfunction: Again press buttons -0-and-1- to enter "ENGINE ELECTRONICS" address word 01. Display will read - "RAPID DATA TRANSFER " "01-ENGINE ELECTRONICS ". Press -Q- button to confirm input. Display indicates ECM identification and coding. Display will read (for example), " 4AO907551AA 2.21 R5 MOTR RHV HS D" "CODING 4". For ECM identification (version). See ECM IDENTIFICATION. Also see, ECM CODING. Press -right arrow- button. Display will read - " RAPID DATA TRANSFER" "SELECT FUNCTION XX" NOTE: Press the HELP button to print a list of selectable functions. Press buttons -0- and -2- to select "CHECK DTC MEMORY" function 02. Display will read - "RAPID DATA TRANSFER" "02-CHECK DTC MEMORY". Press -Q- button to confirm input. Display will show code recognized or not recognized. Display will read - " X DTC RECOGNIZED" -or- "NO DTC RECOGNIZED". NOTE: Printer functions to be aware of: If the printer is switched ON, stored DTC's will be displayed in sequence and then printed. If the printer is switched OFF, Press the -right arrow- button to display the next DTC. DTC 00513 "ENGINE SPEED SENSOR-G28" will always be displayed or printed if the ignition is switched on and the engine is not running. Ignore this display in this situation. After the last DTC is displayed or printed: Press the -right arrow- button. Display will read - "RAPID DATA TRANSFER" " SELECT FUNCTION XX".
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
