1991 Audi 90 Quattro Service and Repair Manual

This 1991 Audi 90 Quattro factory service and repair manual is written for the 20v sedan with the 2.3L inline-five (engine code 7A), so the specifications, wiring, and torque values inside track this exact configuration instead of a generic 90-series printing.

Engines covered

• 2.3L inline-five — DOHC, naturally aspirated, gasoline

Body styles covered

• 4-door sedan

Trims covered

• 20v

Known issues on the 1991 90 Quattro. Two recalls are on federal record for this model year. The first covers the transaxle: differential oil is lost over time to evaporation, and low fluid levels bring on premature bearing and gear wear and eventual failure of the differential, which can cause a sudden loss of drive-wheel power or locked front wheels. The second covers the front airbag sensor, which may not meet Audi's durability standards over the vehicle's lifetime and can misfire, deploying the airbag without warning. Owners have filed 3 complaints for the year. The factory diagnostic and repair procedures behind each of those systems are here.

From tracking a slow differential oil loss to inspecting the front airbag sensor circuit, it keeps you on the OEM procedure and the correct specification for your specific 1991 90 Quattro.