1991 Audi 100 Quattro Service and Repair Manual

This manual is built specifically for the 1991 Audi 100 Quattro, covering the 2.3L inline-five (engine code NF) as Audi documented it for this exact year, engine and trim, so the torque values and procedures inside match your car instead of a generic 100-series writeup.

Engines covered

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

Body styles covered

• 4-door sedan

Trims covered

• Base

Known issues on the 1991 100 Quattro. Four recalls are on federal record for this model year. The first covers the transaxle: differential oil is lost over time through evaporation, and the resulting low oil level causes premature bearing and gear wear that can lead to differential failure, with the drive wheels losing power or the front wheels locking and causing rapid deceleration. The second covers the rear speaker amplifiers, where a leaking capacitor can create an unwanted conductive path, raising the risk of amplifier overheating and fire. The third covers the trunk jack instruction label, which is incorrect for the jack supplied with the vehicle, risking injury if the jack is used improperly and collapses. The fourth covers the frontal air bag sensor, which may not meet durability standards over the vehicle's life and could malfunction, causing inadvertent deployment. Owners have filed 10 complaints for the year. The factory diagnostic and repair procedures behind each of those systems are here.

Whether you're topping off the transaxle, tracing a speaker amplifier fault, or working through a front air bag sensor check, it keeps you on the OEM procedure and the correct specification for your specific 1991 100 Quattro.