Engine Controls - Self-Diagnostics - 2.7L Turbo: Introduction

CAUTION: When battery or ECM is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until adaptation systems have completed a relearn cycle. See 2002 COMPUTER RELEARN PROCEDURES or 2003 COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

NOTE: Before disconnecting battery, obtain anti-theft code for radio. After reconnecting battery, re-code and check operation of anti-theft radio. Also check operation of clock and power windows. On vehicles equipped with Audi Telematics by OnStar®, switch-off the emergency (back-up) battery for the Telematic/Telephone Control Module prior to disconnecting vehicle battery. Emergency battery is turned on and off using VAG 1551/VAG 1552 or VAS 5051/VAS 5052 scan tool in address word 75 - TELEMATICS set to function 10 - ADAPTATION CHANNEL 08.

To properly diagnose vehicle, vehicle manufacturer recommends use of Scan Tool (VAG 1551/VAG 1552, VAS 5051/VAS 5052) and Test Box (VAG 1598). Generic scan tools may not be capable of performing all diagnostic functions e.g. Readiness Code, Idle Check and Automatic Test Sequence etc. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedures. Ensure ignition switch is in OFF position when performing resistance tests.

The 2.7L bi-turbo (twin turbo) with engine code APB is standard equipment on S4. The 2.7L engine is equipped with a DOHC bi-turbo with direct ignition, electronic turbo boost regulation, 5 valves per cylinder, ME 7.0 Motronic with electronic throttle control.

The Motronic Engine Control Module (ECM) has ability to control ignition and fuel injection systems, as well as monitoring of systems for malfunctions. Engine performance diagnoses is accomplished using VAS 5051 scan tool or VAG 1551 scan tool along with VAG 1598/31 test box. Scan tool allows for diagnosis via Diagnostic Trouble Codes (DTCs) as well as ability to view real time data streaming of various actuators and sensors. Actuators can be commanded On or Off by scan tool to verify operation and aid in diagnostics.