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.
Retrieving & Clearing Codes
1996 Audi A4 Base, StandardSECTION Retrieving & Clearing Codes
- Ensure all fuses are okay. Ensure ground connections at engine and transmission are clean and tight. Open rear passenger ashtray in center console, and remove cover for Data Link Connectors (DLC). Turn ignition off. Using Cable (VAG 1551/3), connect Scan Tester (VAG 1551) to DLC.
- Two displays will alternately appear on scan tester. If necessary, press right arrow button on scan tester to maneuver through program sequence. Press PRINT button to turn on scan tester printer. Turn on ignition or start engine. Press AUTO button. Press "1" button to select RAPID DATA TRANSFER function.
- With RAPID DATA TRANSFER displayed on scan tester, press "0" and "8" buttons to select A/C/HEATING ELECTRONICS function. Press "Q" button to enter input. If CONTROL MODULE DOES NOT ANSWER, K WIRE NOT SWITCHING TO POSITIVE, or if NO SIGNAL FROM CONTROL MODULE is displayed, press HELP button to print out a list of possible causes. Check DLC wiring for battery voltage and ground.
- If FAULT IN COMMUNICATION BUILD-UP is displayed, repair any scan tester malfunctions. Also check voltage supply and ground circuits to A/C compressor clutch control module. After repairing problem, press "0" and "8" buttons to select A/C/HEATING ELECTRONICS function. Press "Q" button to enter input.
- Scan tester should display TESTER SENDS ADDRESS WORD 08, then A/C compressor control module identification and coding should be displayed. A list of On Board Diagnostic (OBD) functions can be printed out by pressing HELP button. See OBD FUNCTIONS .
- Press right arrow button on scan tester until RAPID DATA TRANSFER is displayed on scan tester. When SELECT FUNCTION XX is displayed, press "0" and "2" buttons to select INTERROGATE DTC MEMORY function. Press "Q" button to enter input.
- An X FAULTS RECOGNIZED (number of codes stored) or NO FAULT RECOGNIZED message will be displayed. Press right arrow button. Diagnostic trouble codes, if any, will be displayed and printed one after another. After last DTC has been displayed, turn ignition off. See appropriate DTC test.
- Repair A/C system malfunctions (if any). After repairs, test drive vehicle once more. Check for diagnostic trouble codes once again. If A/C compressor clutch does not engage, even though no DTC was recognized, perform MEASURING VALUE BLOCK function and OUTPUT DIAGNOSTIC TEST MODE .
OBD FUNCTIONS (1)
| Function | Description | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 01 | Checking A/C-Heater Control Panel Coding | ||||||||||
| 02 | Checking DTC Memory | ||||||||||
| 03 (2) | Output Diagnostic Test Mode | ||||||||||
| 04 (3) | Basic Setting | ||||||||||
| 05 | Erasing DTC Memory | ||||||||||
| 06 | Ending Output | ||||||||||
| 07 (4) | Coding A/C-Heater Control Panel | ||||||||||
| 08 (5) | Reading Measuring Value Block | ||||||||||
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RENDER: 1.0x
NO RELATED
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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.