2018–2026 Audi Q8 (4M) Service & Repair Manual PDF

Description

Audi Q8 (Typ 4M) Service and Repair Manual — 2018 onward

The Q8 is a modern, software-dense luxury SUV, and it demands a different mindset from an older Audi. Every engine runs a 48-volt mild-hybrid system that can shut the engine off while you coast and restart it without warning. The air suspension is standard, not optional. The driver-assistance suite needs recalibrating after work as ordinary as a windscreen replacement. And component replacement almost always requires coding — a mechanically perfect repair with no software step is an incomplete repair.

This documentation is built around that reality: correct procedure, correct calibration, correct coding, on a car where guesswork is expensive.

What the Q8 4M is

Launched in 2018 on the MLB Evo platform, the Q8 is Audi’s flagship coupé-SUV, sharing its bones with the Q7, the Porsche Cayenne, the Bentley Bentayga and the Lamborghini Urus. It is a five-seat, permanent-quattro SUV positioned above the Q7.

A facelift arrived for the 2024 model year (from late 2023), bringing octagonal grille detailing, revised bumpers, OLED tail lights and laser high-beam lighting, along with interior and software updates.

Note: this set covers the standard Q8 range — the 55 TFSI petrol, the 45 and 50 TDI diesels and the TFSI e plug-in hybrid. The SQ8 and RS Q8 are separate, higher-output V8 cars with their own documentation, linked at the bottom of this page.

Engines covered

Model	Engine	Notes
55 TFSI	3.0 V6 petrol	340 PS, 48V MHEV, quattro
45 TDI	3.0 V6 diesel	231 PS, 48V MHEV, twin-dosing SCR
50 TDI	3.0 V6 diesel	286 PS, 48V MHEV, twin-dosing SCR
55 TFSI e / 60 TFSI e	3.0 V6 petrol PHEV	High-voltage plug-in hybrid

All the combustion engines are the EA839 3.0 V6 in petrol or diesel form, chain-driven and mated to the 48-volt mild-hybrid system as standard. The plug-in hybrid adds a full high-voltage traction system on top — a different animal, and treated as one.

The 48-volt mild-hybrid system

Every Q8 runs a 48V belt-driven alternator-starter with its own lithium-ion battery and a DC/DC converter feeding the 12V system. It restarts the engine while coasting, recuperates under braking, and keeps the belt drive under load in both directions.

The BAS unit, the 48V battery, the converter, the de-energisation sequence required before working on the belt drive, and the system’s fault codes are all covered. This is not a high-voltage traction system, but it is not a conventional alternator either — and the engine can start unexpectedly if you do not isolate it first.

Air suspension — standard, and its own diagnostic world

The Q8’s adaptive air suspension is standard equipment, which means almost every one of these cars has it, and almost every one will eventually need it diagnosed.

A Q8 sitting low on one corner is not automatically a failed strut. It can equally be the valve block, an air line, or a level sensor — and on a car this size, replacing the wrong one is a serious bill. The diagnostic sequence, the compressor duty-cycle limits, the calibration after any component change, and the ride-height specification are all documented, along with the optional rear-wheel steering where fitted.

Transmission and quattro

Eight-speed tiptronic (ZF 8HP) — the torque converter automatic across the range. Fluid procedure, solenoid diagnosis, adaptation, and the mild-hybrid integration.

quattro with self-locking centre differential — permanent, mechanical, with a rear sport differential on some cars. Inspection, fluid, the transfer case and the final drives. No Haldex.

Driver assistance and calibration

The Q8 carries front radar, a windscreen camera, corner radars and a full ultrasonic array, plus night vision and adaptive cruise on higher specifications.

These require calibration after related work: the camera after a windscreen replacement, the radar after any front-end repair or alignment change. Skipping it leaves emergency braking and lane keeping working from bad data. The calibration procedures, targets and repeat conditions are all covered.

Electrical, diagnostics and infotainment

Full wiring diagrams by model year, connector views and pinouts, CAN, LIN and Ethernet topology, the gateway and the many domain modules, immobiliser and key adaptation, and fault code tables with measuring block references.

Infotainment covers the dual-touchscreen MMI and the Virtual Cockpit, including the software changes brought by the 2024 facelift, and the OLED tail lights and laser high-beam modules, which are addressed as software components requiring coding after replacement.

Service and known items you will be looking up

The Q8 is recent enough that it does not have a deep catalogue of failures, and this set does not invent one. What it documents thoroughly is correct service and the issues that have emerged:

• 48V mild-hybrid faults — BAS unit, 48V battery or converter. Symptoms from a warning light to a no-restart after coasting.
• Air suspension diagnosis — strut vs valve block vs air line vs sensor, in the correct order.
• EA839 water pump and thermostat — coolant loss on the V6.
• Diesel AdBlue / twin-dosing SCR — dosing pump faults, crystallisation, level sensor errors and forced regeneration.
• Carbon buildup on intake valves — inherent to direct injection on the petrol V6.
• Camera and radar calibration after glass or front-end work — required, and frequently skipped.
• Electronic parking brake — service-mode retraction before rear pad replacement.
• MMI and Virtual Cockpit software faults — freezes and reboots, usually software rather than hardware.
• Coding and adaptation after module replacement — required across most systems on this car.

What’s inside this manual set

• Engine — removal, overhaul, timing, torque specifications
• 48-volt mild-hybrid system — BAS, battery, converter, de-energisation
• Fuel, ignition and forced induction; AdBlue/SCR on the diesels
• Cooling and lubrication
• Transmission — eight-speed tiptronic and final drives
• Transfer case, driveshafts and the quattro centre differential
• Brakes, including ABS, ESP and the electronic parking brake
• Suspension and steering — adaptive air suspension, rear-wheel steering
• Driver assistance — radar and camera calibration procedures
• Body — panel repair, body dimensions, trim removal
• Electrical — full wiring diagrams, connector views, pinouts
• Diagnostics — fault codes, measuring blocks, adaptation, coding
• Maintenance schedules and service reset procedures

Format and delivery

Supplied as a set of searchable PDF files covering the standard Q8 range, pre-facelift and the 2024 facelift. 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

Does this include the SQ8 or RS Q8?

No. The SQ8 and RS Q8 are separate cars — twin-turbo V8s with their own drivetrains — and they have their own documentation, linked below. This set covers the standard Q8: the 55 TFSI, the 45 and 50 TDI, and the TFSI e plug-in hybrid.

My Q8 has dropped on one corner. Is it the air strut?

Not necessarily. On a car where the air suspension is standard, that symptom can be the valve block, an air line, or a level sensor just as easily as a strut. The documentation gives the diagnostic sequence so you replace the right part rather than guessing on an expensive component.

Is the 48-volt system covered?

Yes — the belt-driven alternator-starter, the 48V battery, the DC/DC converter and the de-energisation sequence required before working on the belt drive. The engine can restart itself while coasting, so this matters.

Is the plug-in hybrid covered?

Yes, including high-voltage safety procedures and battery isolation. High-voltage work requires proper training, tools and PPE — the documentation is clear about where that line falls.

I replaced the windscreen and now the assistance systems are behaving oddly. Is that in here?

Yes. The forward camera sits behind the glass and must be recalibrated after replacement, or lane keeping and emergency braking work from bad geometry. The procedure and targets are documented.

Does it cover the 2024 facelift?

Yes. Both the original cars and the facelifted 2024-onward models — with the OLED tail lights, laser high beam and updated software — are covered.

Will this work with VCDS or ODIS?

Yes. Fault codes, measuring blocks and adaptation channels map directly to both — including the air suspension controller and the assistance-system calibrations.

Related manuals

• Audi SQ8 manuals
• Audi RS Q8 manuals