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C4 Sedan · Avant

Audi 100 / A6 · Sedan · Avant · 1990–1997

Aero-era big Audi that became the first A6.

Production run

1990–1997

Engines covered

3

Avg. part price

—

19902026

Interactive systems map

Inspect the C4

Tap a hotspot to inspect that system

Systems map

Where it goes wrong

Each numbered hotspot counts the documented failure points in that area. Select one to see the specifics for this chassis and engine.

Failure points by system

Engine5

Cooling1

Fuel1

Documented issues per engine

4

V6 2.8

4

AHA

4

1.9 TDI

Known weak points

What breaks on the C4

Timing beltDiagnose →Head gasket at very high mileageDiagnose →Timing belt and tensionerDiagnose →Coolant seepage at the blockDiagnose →PD injector seals and loomDiagnose →Cam wearDiagnose →

Guides & playbooks

C4 playbooks

Maintenance scheduleGive me a mileage-based maintenance schedule for a Audi 100 / A6 C4, including the items the factory schedule skips.Buyer's inspectionI'm inspecting a used Audi 100 / A6 C4. What exactly should I check, test drive and look for underneath?Build planPlan a staged performance build for a Audi 100 / A6 C4 that stays reliable as a daily driver.Fault code lookupI have a fault code on my Audi 100 / A6 C4. Walk me through what it means and how to confirm the cause.

Fits your C4

Parts & tools

Full catalog & export

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