Audi A4 S4 Workshop Service Manual

Getting the Factory Service Information for B6/B7 A4 and S4 Models

The Audi A4 S4 Workshop Service Manual covers the B6 (2002-2008) and B7 (2005-2008) generations. That means 2002 through 2008 B6, and 2006 through 2008 S4 with the 4.2L V8. You'll find wiring diagrams, torque specs, procedures for everything from thermostat replacement to gearbox rebuilds, along with fault code definitions and adaptation values. The documentation is divided into vehicle systems, not by repair task, which trips up a lot of first-time users. The manual is structured around Audi's own groupings: engine mechanical, fuel injection, electrical systems, transmission, suspension, braking, body electronics, climate control, and diagnostic procedures. Each section has sub-procedures with step numbers, illustrations, and critical notes flagged in red or with warning icons. The wiring diagrams use standard European color coding with wire cross-sections and connector pin assignments. Torque values are in Newton-meters throughout. If you're working on a right-hand drive UK or Japanese import, the wiring diagrams are identical, but the diagnostic connector locations can differ slightly — I learned that the hard way on a 2005 S4 imported from Japan where the OBD port had a different mounting bracket than the European version. The adaptation values section is where most people hit walls. When you're coding a new module or doing a throttle body adaptation after an intake service, the manual lists the standard ranges for each parameter. Going outside those ranges usually means something mechanical is wrong, not just a coding issue. People chase electrical problems when the real issue is carbon buildup or a vacuum leak, and they waste days on it.

The fault code tables aren't exhaustive. They cover common DTCs and their likely causes, but they don't include every possible combination. Audi uses a generic OBD2 structure for emissions-related codes and proprietary codes for body and chassis modules. The proprietary codes require a VAG-compatible scanner — an OBDLink or VCDS will pull them, but a cheap blue-tooth dongle from Amazon won't show half the system addresses. This matters because the B6/B7 platform has sixteen control module addresses, and missing address 19 (CAN gateway) means you won't see network communication faults that show up as ghost codes in other modules. I ran into a situation last year on a 2004 A4 2.0T where the timing chain had stretched and the camshaft position sensor was reading marginal. The manual lists the chain tensioner specs and the procedure for replacing the timing cover, but what it doesn't emphasize enough is the oil passage restriction in the tensioner bracket on those early 2002 to 2005 engines. If you don't clean the oil screen in the bracket during reassembly, the new tensioner starves within a few thousand kilometers. I found a Reddit thread from someone who did exactly that — rebuilt the timing chain with fresh parts, heard the rattle return at 4,000 miles, torn it back out, and found the tensioner bracket screen completely clogged with debris. The fix was a brass pick and brake cleaner. Five minutes of additional work that probably saved a $3,000 engine replacement.

How to Access the Documentation

There are two legitimate paths to the factory service data. The first is through a VAS diagnostic system or a software package that licenses Audi technical information. These require paid subscriptions and are aimed at professional shops. The pricing runs roughly €3,000 to €6,000 per year depending on the module bundle, and you need a valid business credentials to register. For a single-owner DIYer, this is overkill unless you're planning to work on Audis regularly. The second path is through unofficial reproduction PDFs that circulate on enthusiast forums and technical archive sites. These are scanned or digitally recreated from the factory documentation and aren't sanctioned by Audi. They're freely available on several community-run sites, though the quality varies — some versions have garbled pages where the original diagrams were heavily shaded, and the search function in PDF form doesn't always index the smaller print properly. I keep a local copy on an SSD and use a dedicated PDF reader with OCR enabled so I can search by component name rather than hunting through page numbers. A practical workaround I use is running the PDF alongside a live VCDS connection. When I need a wiring diagram for the N75 valve on a B6 2.0T, I pull up the relevant section, find the wire colors and connector pinout, then verify with VCDS data while the engine is running. The manual gives you the target — green-yellow wire, pin 3 at connector T32a — but verifying continuity with a multimeter and watching the live boost command data tells you whether the wiring actually matches the diagram or if someone spliced it improperly during a previous repair.

Common Mistakes That Waste Time

People skip the preparation steps. The manual opens most procedures with a prerequisites section: vehicle lift points, battery disconnect sequence, special tools required. On the B6 A4, the front subframe bolts require a 21mm socket and a long breaker bar, and the manual specifies a torque sequence for the subframe-to-body fasteners. Skipping the torque sequence and just tightening them down in any order leads to misalignment that causes premature bushing wear and vague steering feel. I've seen three cars come through where the alignment was impossible to dial in until the subframe bolts were removed and reinstalled in the proper sequence with the suspension at ride height. Another frequent error is misreading the coolant drain and refill procedure. The 2.0T engine uses a pressurized cooling system with a specific bleeding sequence that involves opening the bleed screw at the thermostat housing with the heater on max and the expansion tank cap off. The manual lays this out, but people skip it and just fill the system and drive. Air pockets in the B6 cooling system cause overheating under load and can damage the water pump impeller over time. The correct procedure takes about twenty minutes and prevents the tow truck call three weeks later. The S4 4.2L V8 has its own quirks. The camshaft adjustment sensors on each bank are prone to failure around 90,000 miles, and the manual gives the resistance specification — between 10 and 20 ohms at room temperature. If you measure outside that range, replace both sensors on the same bank even if only one threw a code. The control modules communicate between banks, and a marginal sensor on one side causes adaptation drift on the other. I replaced one sensor on a 2006 S4, cleared the codes, and had the same code return on the opposite bank within a week. Swapped that one too and the idle smoothed out immediately.

What the Manual Doesn't Cover Well

The electrical troubleshooting section assumes you have access to a wiring diagram for the specific VIN year, which is fine if you're working from the documentation, but the diagrams for 2002 to 2004 models differ from 2005 onward due to the transition to a modified CAN bus architecture. Audi updated the gateway module and some sensor networks between model years, so a diagram from a 2003 manual won't match a 2007 car even though they're both B6 generation. Always verify the model year against the diagram header before tracing circuits. Body repair procedures, particularly for crash damage, are thin on the B6 platform. The manual covers panel replacement and welding points, but the adhesive applications and sealant specifications for structural bonding are minimal compared to what you'd find in a professional collision repair database. If you're doing frame straightening or unibody repair, supplement the manual with an OEM body repair guide or a professional-level resource. The factory service manual alone will leave gaps on structural adhesive cure times and spot weld specifications. Transmission rebuild information exists but is oriented toward a professional shop environment. The manual describes the disassembly sequence for the 01E automatic in the S4, but many fastener torques and clearance measurements assume specialized equipment like a dial indicator stand and a torque converter holding fixture. If you don't have those, you're working blind on critical clearances. A professional rebuild facility with the right fixtures will do a more reliable job than a well-equipped home mechanic following the manual alone for the transmission internals.

Practical Usage Tips

Bookmark the diagnostic connector locations early. On the B6 A4, the OBD2 port is under the dashboard on the driver's side, but the main diagnostic test lead connector for VAS equipment is behind the passenger-side air filter housing. If you're troubleshooting an electrical gremlin and need to probe live circuits, having both locations mapped out saves you from tearing interior trim apart mid-diagnosis. The torque specs are non-negotiable on critical components. The 2.0T head bolts use a torque-to-yield process with a specific three-step sequence: first stage to 25 Nm, second to 90 degrees, third to another 90 degrees. Using an impact wrench or skipping the angle steps will stretch the bolts unevenly and lead to head gasket failure. I once saw a car with repeated overheating and coolant loss where the previous owner had simply torqued the head bolts to 25 Nm and stopped. The manual is clear on the sequence — there's no ambiguity — but people skip steps when they're impatient or trying to save time on a job they think they know. Keep the manual as a reference, not a substitute for diagnostic reasoning. The service procedures tell you how to replace a part. They don't always tell you whether replacing that part will fix your specific problem. A no-start condition on a B6 2.0T could be the immobilizer, the crankshaft position sensor, the fuel pump relay, or the timing chain tensioner that failed and jumped teeth. The manual has procedures for testing each of those, but you need to narrow the cause before you start pulling components. Start with live data — fuel trims, ignition timing advance, crank and cam sync status — and then follow the appropriate diagnostic tree. The manual is your road map once you know which direction you're heading.

The documentation is accurate for the years it covers. It's not comprehensive for every variant — the 3.0L V6 in the S4 has different valve cover gasket procedures than the 4.2L, and the quattro AWD system diagnostics differ between the manual transmission and automatic versions. But for the core mechanical and electrical systems on the B6 and B7 A4 and S4, it remains the most detailed single-source reference available. The unofficial PDF copies hold up well for home mechanics who want factory-level detail without paying for professional software access.