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Audi · Known Issues

1991 Audi 100 Problems: 5 Known Issues

1991 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated August 2026

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Issue summary

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1991 Audi 100 has 5 documented known issues, with 4 rated critical. The most serious are 1990-1991 Audi 100 3-Speed Automatic Transaxle Recall 93V006, Hydraulic Assist System Leak (Pentosin) ($500-$2,000 repair), 1991-1992 Audi 100 Rear-Speaker Amplifier Recall 01V324 and Power Steering Rack Seal Leak ($500-$1,200 repair). Across all issues with published estimates, repair costs range from $50 to $2,000. DIY maintenance guides at au7o.io.

In This Article

  • 100 Transmission1
  • 100 Suspension1
  • 100 Electrical1
  • 100 Steering1
  • 100 Engine1
  • Recalls9
  • FAQ
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In This Article

  • Transmission1
  • Suspension1
  • Electrical1
  • Steering1
  • Engine1
  • Recalls9
  • FAQ

All 5 Known Issues

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ALL YEARS19941993199219911990

On the 1990-1991 Audi 100, nHTSA campaign 93V006 covers 1990-1991 Audi 100 passenger cars equipped with a 3-speed automatic transmission. The campaign states that differential oil could be lost over time through evaporation, causing premature bearing and gear wear. Eventual differential failure could remove drive to the wheels or, in an extreme case, lock the front wheels and cause rapid deceleration. This is not a generic harsh-shift, solenoid or OBD-II DTC diagnosis.

Common Symptoms

  • Loss of drive if the differential fails
  • Possible front-wheel lock in an extreme differential failure

How to Fix

Check the VIN and campaign history with Audi or NHTSA. The historical campaign remedy drained the differential gear oil and replaced it with oil having higher-performance characteristics. Because these vehicles are more than 15 years old, confirm current remedy availability and any cost with Audi before service. Diagnose a present shift complaint separately and do not order a solenoid or filter kit from this card.

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NHTSA Verified
High ConfidenceVerifiedReviewed Jul 2026

On the 1990-1994 Audi 100, the Audi 100 uses a complex mineral oil hydraulic system (Pentosin) that powers steering, brakes, and self-leveling suspension. Hoses, pump seals, and rack seals develop leaks, causing loss of power assist to steering and brakes simultaneously.

Common Symptoms

  • Heavy steering
  • Brake pedal hard
  • Hydraulic fluid under car
  • Suspension sag
  • Pump whining noise

How to Fix

Typical repair cost:$500 - $2,000

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Community Reported
Medium Confidence

On the 1991-1992 Audi 100, nHTSA campaign 01V324 covers 1991-1992 Audi 100 passenger vehicles. An electrolytic capacitor in each rear-speaker amplifier could leak electrolyte; with humidity, that leakage could create an unwanted conductive path, overheat the amplifier and create a fire risk. The campaign does not validate a universal engine or charging wiring-harness insulation defect.

Common Symptoms

  • Heat, smoke or burning odor near a rear-speaker amplifier

How to Fix

Check the VIN and campaign-completion history with Audi or NHTSA. The historical remedy replaced the rear-speaker amplifier assemblies. Confirm current remedy availability and cost with Audi because of the vehicle age. Treat heat, smoke or a burning smell from the rear-speaker area as an immediate stop-and-inspect condition.

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On the 1990-1994 Audi 100, the hydraulic power steering rack develops leaks from the input shaft seal and inner tie rod boots. Pentosin hydraulic fluid weeps and eventually pours from the rack, causing heavy steering and low fluid warnings.

Common Symptoms

  • Power steering fluid leak
  • Heavy steering at low speed
  • Whining power steering pump
  • Fluid on garage floor
  • Steering assist intermittent

How to Fix

Replace or rebuild power steering rack. Use Pentosin CHF 11S fluid only — conventional ATF will destroy seals. Flush entire system when replacing rack. Check pump for whining which indicates damage from running low.

Typical repair cost:$500 - $1,200

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Community Reported
Medium Confidence

On the 1990-1994 Audi 100, vacuum hoses throughout the engine bay become brittle, crack, and leak with age. Causes rough idle, failed emissions, inoperative climate control flaps, and cruise control failure. The Audi 100 uses vacuum for numerous subsystems.

Common Symptoms

  • Rough idle
  • Climate control stuck on defrost
  • Cruise control inoperative
  • Lean fault codes
  • Hissing noise from engine bay

How to Fix

Replace all vacuum hoses with silicone or OEM-quality rubber hose. Create a vacuum line diagram before removing old lines. Test each vacuum-operated system after replacement. Inspect check valves and vacuum reservoir.

Typical repair cost:$50 - $200

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NHTSA Recalls9 recalls

FUEL SYSTEM, GASOLINE:FUEL INJECTION SYSTEM

VEHICLE DESCRIPTION: PASSENGER VEHICLES EQUIPPED WITH V6 ENGINES. AN INTERNAL SEAL OF THE FUEL INJECTOR CAN MALFUNCTION, ALLOWING FUEL LEAKAGE IN THE ENGINE COMPARTMENT.

Campaign #98V33200023/12/1998

EQUIPMENT:ELECTRICAL:RADIO/TAPE DECK/CD ETC.

VEHICLE DESCRIPTION: PASSENGER VEHICLES. AN ELECTROLYTIC CAPACITOR CONTAINED IN THE AMPLIFIER FOR EACH REAR SPEAKER COULD LEAK AN ELECTROLYTE, WHICH MAY IN TIME AND IN THE PRESENCE OF HUMIDITY, CAUSE AN UNWANTED CONDUCTIVE PATH.

Campaign #01V32400010/10/2001

EQUIPMENT:MECHANICAL:ACCESSORY SCISSOR/SCREW/BOTTLE JACK/LIFT

INSTRUCTION LABEL IN THE TRUNK OF VEHICLE IS INCORRECT FOR THE JACK SUPPLIED WITH THE VEHICLE.

Campaign #91V05000002/04/1991

FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS

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Frequently Asked Questions

What are the most common Audi 100 problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1991 Audi 100 has 5 documented issues. The most frequently reported are: 1990-1991 Audi 100 3-Speed Automatic Transaxle Recall 93V006, Hydraulic Assist System Leak (Pentosin), 1991-1992 Audi 100 Rear-Speaker Amplifier Recall 01V324. Of these, 4 are rated critical and should be addressed promptly.

Is the Audi 100 reliable?

The 1991 Audi 100 has 5 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 4 issues are rated critical: 1990-1991 Audi 100 3-Speed Automatic Transaxle Recall 93V006 and Hydraulic Assist System Leak (Pentosin) and 1991-1992 Audi 100 Rear-Speaker Amplifier Recall 01V324 and Power Steering Rack Seal Leak. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Audi 100 problems?

Repair costs for known Audi 100 issues range from $50 to $2,000, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 1990-1991 Audi 100 1990-1991 Audi 100 3-Speed Automatic Transaxle Recall 93V006?

NHTSA campaign 93V006 covers 1990-1991 Audi 100 passenger cars equipped with a 3-speed automatic transmission. The campaign states that differential oil could be lost over time through evaporation, causing premature bearing and gear wear. Eventual differential failure could remov… Severity: high.

What is the 1990-1994 Audi 100 Hydraulic Assist System Leak (Pentosin)?

The Audi 100 uses a complex mineral oil hydraulic system (Pentosin) that powers steering, brakes, and self-leveling suspension. Hoses, pump seals, and rack seals develop leaks, causing loss of power assist to steering and brakes simultaneously. Repairs typically run $500-$2,000. Severity: high.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data compiled from NHTSA recalls, manufacturer TSBs, automotive forums, and AI-assisted research. No aggregated owner-report counts available for this vehicle yet.

VEHICLE DESCRIPTION: PASSENGER VEHICLES. THE FUEL FEED LINE CONNECTING THE FUEL FILTER TO THE ENGINE DELIVERED BY THE SUPPLIER FOR USE IN THESE VEHICLES MAY HAVE BEEN IMPROPERLY MANUFACTURED.

Campaign #00V08400020/03/2000

ELECTRICAL SYSTEM:IGNITION:SWITCH

DEFECTIVE IGNITION SWITCHES WERE IMPROPERLY MANUFACTURED AND CAN CAUSE SOME ELECTRICAL ACCESSORIES TO MALFUNCTION.

Campaign #96V01700029/01/1996

+ 4 more recalls. Check all on NHTSA.gov

Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.

What is the 1991-1992 Audi 100 1991-1992 Audi 100 Rear-Speaker Amplifier Recall 01V324?

NHTSA campaign 01V324 covers 1991-1992 Audi 100 passenger vehicles. An electrolytic capacitor in each rear-speaker amplifier could leak electrolyte; with humidity, that leakage could create an unwanted conductive path, overheat the amplifier and create a fire risk. The campaign d… Severity: high.

What is the 1990-1994 Audi 100 Power Steering Rack Seal Leak?

The hydraulic power steering rack develops leaks from the input shaft seal and inner tie rod boots. Pentosin hydraulic fluid weeps and eventually pours from the rack, causing heavy steering and low fluid warnings. Repairs typically run $500-$1,200. Severity: high.

What is the 1990-1994 Audi 100 Vacuum Hose Deterioration Causing Multiple Issues?

Vacuum hoses throughout the engine bay become brittle, crack, and leak with age. Causes rough idle, failed emissions, inoperative climate control flaps, and cruise control failure. The Audi 100 uses vacuum for numerous subsystems. Repairs typically run $50-$200. Severity: medium.