1994–1997 Audi S6 C4 (4A) Service and Repair Manual PDF

Description

Audi S6 (Typ 4A, C4) Service and Repair Manual — 1994 to 1997

This is the Ur-S6 — the original, and for many the best. Its heart is the AAN 2.2-litre turbocharged inline-five, a direct descendant of the engine that powered Audi’s Sport Quattro and its rally cars, and the source of that unmistakable off-beat five-cylinder warble. If you own one, you are keeping a genuine piece of Audi’s performance history running — and the knowledge to do it properly is getting harder to find every year.

Later cars added a 4.2 V8 option, and a tiny run of the ferocious S6 Plus closed out the C4 line. This documentation covers all of them, and keeps the very different engines apart.

What the S6 C4 is

Introduced in late 1994, the S6 is the high-performance version of the C4 A6 — and it is essentially the renamed, lightly revised continuation of the earlier Ur-S4. It was sold as a saloon (4A5) and an Avant (4A9), always with quattro, using a Torsen type-1 centre differential: permanent, mechanical all-wheel drive with no Haldex, no pump and no filter.

The range grew over its short life:

• 2.2 turbo inline-five (AAN) — the signature engine, 230 PS, with a six-speed manual (five-speed in North America).
• 4.2 V8 (AEC) — an optional 290 PS V8, standard automatic with an optional six-speed manual.
• S6 Plus — the swan song. Built by quattro GmbH for the 1997 model year only, just 952 made, with a 326 PS version of the 4.2 V8 (AHK — the same engine later seen in the S8 as AKH), six-speed manual only, bigger brakes and revised suspension.

The AAN inline-five turbo — the heart of the car

The 2.2 20-valve turbocharged five is what makes an S6 an S6, and it is nothing like a modern engine to work on.

• Bosch Motronic management — the engine control, knock sensing and boost control that run the turbo. Diagnosis of running faults, boost problems and the safety cut.
• Turbocharger and boost system — the KKK turbo, wastegate, and the plumbing that is central to the car’s performance and its faults.
• Timing belt — an interference engine. Interval, tensioner, water pump and locking positions.
• Fuelling — the injection system, fuel pressure and the cold-start behaviour that trips people up.

This engine responds famously well to correct maintenance and just as dramatically to neglect. Getting the boost system, the timing and the fuelling right is the difference between the car people fall in love with and a tired, hesitant one.

The V8 cars (4.2 AEC and S6 Plus AHK)

The optional V8 is a completely different engine — a 32-valve quad-cam unit, belt-and-chain driven, with per-bank camshaft chains and their tensioners. A start-up rattle on these is far more often the chain tensioners than the belt, and the two are documented separately so you fix the actual fault.

The S6 Plus’s AHK is the most highly developed of these, and its overlap with the later S8 engine (AKH) occasionally helps with parts on an extremely rare car. The documentation notes where that overlap is real.

Transmission and quattro

Six-speed manual (five-speed in North America) — the enthusiast’s choice, standard on the inline-five and the S6 Plus. Clutch, dual-mass flywheel, linkage and fluid.

Four-speed tiptronic automatic — standard on the V8 cars. Fluid procedure, solenoid diagnosis and the adaptation reset.

Torsen type-1 centre differential — mechanical, permanent, torque-sensing, with the rear final drive. Inspection and fluid. No Haldex anywhere.

Chassis, brakes and electrical

The S6 runs uprated brakes over the A6 — larger front discs, four-pad calipers — with the S6 Plus larger still. Suspension, alignment data and the brake specifications are all covered, distinct from the standard A6.

Full wiring diagrams for saloon and Avant, connector views and pinouts, the comfort and central locking systems, the climate control head and its internal codes, xenon lighting where fitted, and fault code tables. The C4 diagnoses over K-line — a modern CAN-only adapter will tell you nothing, and the correct interface and procedure are covered.

Known S6 C4 issues you will be looking up

• AAN boost and turbo faults — low power, overboost or fluctuating boost. The wastegate, the N75, and the plumbing, tested properly.
• Timing belt (inline-five) — interference engine, non-negotiable interval, with the water pump and tensioner.
• V8 cam chain tensioner rattle — start-up rattle on the 4.2 cars, mistaken for the belt.
• Instrument cluster pixel failure — the dot-matrix display fading until unreadable. Cluster removal and repair.
• Front control arms and bushes — wandering steering, clunks and tyre wear from the multi-link front end.
• Bosch Motronic running faults — idle, hesitation and cold-start issues traced to the management and its sensors.
• Secondary air injection — a persistent engine light with no drivability symptom.
• Climate control head failure — dead display or stuck fan, and the internal fault codes.
• Plastic-impeller water pump — disintegrates and overheats. Replace with the belt.
• Wiring loom degradation — cracking insulation with age, especially in the engine bay.
• Parts scarcity — particularly on the S6 Plus, where the S8 engine overlap can help.

What’s inside this manual set

• Engine — the 2.2 inline-five turbo and the 4.2 V8, removal, overhaul, timing, torque
• Turbocharger and boost control (inline-five)
• Fuel and ignition — Bosch Motronic management
• Cooling and lubrication
• Transmission — manual, tiptronic and the Torsen differential
• Clutch, driveshafts and final drives
• Brakes — the uprated S6 and S6 Plus systems, with ABS
• Suspension and steering, with alignment data
• Body — panel repair, body dimensions, trim removal
• Heating, ventilation and air conditioning
• Electrical — full wiring diagrams, connector views, pinouts
• Diagnostics and K-line fault-finding
• Maintenance schedules and service procedures

Format and delivery

Supplied as a set of searchable PDF files covering the S6 across the full C4 run — saloon and Avant, the inline-five and V8 cars, and the S6 Plus. Readable and printable on any device: laptop, tablet, phone, or the workshop PC. No software to install, and no internet connection needed once the files are saved.

Select your year at checkout. After payment, your download link is sent within 24 hours.

Frequently asked questions

Is this the inline-five turbo S6?

Yes — the AAN 2.2 turbocharged inline-five is fully covered, including its Bosch Motronic management, the turbo and boost system, and the timing belt. This is the signature S6 engine, descended from Audi’s rally five-cylinders, and it is the reason many people own the car.

Does it also cover the V8 and the S6 Plus?

Yes. The 4.2 V8 (AEC) and the rare S6 Plus (AHK, 326 PS, 952 built) are both covered, with their belt-and-chain timing documented separately from the inline-five.

My inline-five has boost problems. Is that in here?

Yes. Low power, overboost and fluctuating boost are covered through the wastegate, the N75 and the boost plumbing, tested properly rather than replaced on guesswork.

Does the S6 quattro need a Haldex service?

No. The C4 S6 uses a mechanical Torsen type-1 centre differential. There is no Haldex pump, controller or filter.

Is the S6 Plus engine really related to the S8’s?

Yes — the S6 Plus’s AHK 4.2 is the same engine later seen in the D2 S8 as the AKH, which can help with parts on an otherwise very rare car. The documentation notes where that overlap genuinely applies.

Does it cover the Avant as well as the saloon?

Yes — both the saloon (4A5) and the Avant (4A9), across all engines.

Will this work with VCDS?

Yes, with the correct cable. The C4 diagnoses over K-line rather than CAN — a modern CAN-only adapter will give you nothing. Make sure your interface supports K-line.