According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2003 Audi A8 has 4 documented known issues, with 2 rated critical. The most serious are D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine) ($1,500-$3,000 repair) and Bosch 5.3 ABS Control Module Internal Failure (EBCM) ($200-$600 repair). Across all issues with published estimates, repair costs range from $80 to $3,000. DIY maintenance guides at au7o.io.
Secondary Air Injection P0410/P0411 — Cracked Vacuum Lines, Stuck Combi Valves, Carbon-Clogged Head Ports
70K-180K
D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine)
75K-105K
Bosch 5.3 ABS Control Module Internal Failure (EBCM)
80K-150K
Pentosin CHF11S hydraulic system leaks (power steering pump, rack, hoses)
80K-180K
050K100K150K200K mi
On the 1997-2003 Audi A8, the D2 A8 4.2L V8 (both the early 32-valve ABZ and the later 40-valve AUX/AWN/AKB) is an interference engine driven by a rubber timing belt. The original published interval was 105K miles on the C5 and D2 4.2, until Audi retroactively changed it to 75,000 miles. Many original-owner cars went well past 100k on the factory belt, and high-mileage examples are commonly bought with no timing belt service history. Around the timing belt service interval (75,000 miles), due to age the integrity of the tensioner(s), damper, water pump, and other seals and o-rings are at the end or very near the end of their service life, and some individuals make the mistake of only replacing the timing belt, only for it to fail 10,000-20,000 miles later due to tensioner, idler bearing, or water pump failure. Belt or tensioner failure on this engine bends valves and is typically a total-loss event for an older A8.
Common Symptoms
No symptoms before failure (silent killer)
Possible faint tensioner whine at idle late in belt life
Coolant weep at water pump if pump is original
Engine no-start / no-compression after failure
How to Fix
Procedure: pull the front off / put car in service position, take it apart, lock the cams and R&R the belt + water pump + thermostat and anything else worn or suspicious — consider doing valve cover gaskets and chain tensioner seals too, those seals would be slightly easier to get to while in the middle of the big service. A cam-lock bar is not totally critical, but definitely makes it easier and safer. A full kit (belt, tensioner, damper, idler rollers, water pump, thermostat, accessory belts) should be installed together; budget $1,500–$3,000 with labor at an independent Audi specialist. Replace at 75,000 miles OR 5–6 years, whichever comes first, regardless of what the original owner's book says.
High ConfidenceLast reported by owners May 2026Reviewed May 2026
On the 1997-2003 Audi A8, the Bosch 5.3 ABS/EBCM control module mounted to the side of the hydraulic pump unit suffers from internal solder joint and fine aluminum bond-wire fatigue, causing intermittent then permanent loss of ABS function. The Audi ABS pump & module system has been a very common failure for a long time, and the problem usually starts with the ABS light coming on intermittently but after a while becomes constant. Failed Bosch 5.3 control modules are extremely common in 2000-era Audis. On D2 A8/S8 cars, drivers typically see simultaneous ABS and red brake warning lights with three beeps at startup, and communication with the controller can drop out entirely (Link Error in VAG-COM). The ABS 5.3 system was introduced mid-1997 on the D2 platform; note that the 2002+ S8 reverted to a 5.0-based system, so verify the module on the car before ordering a repair.
Common Symptoms
ABS warning light on (often steady yellow)
Red brake warning light on simultaneously
Three beeps at startup
Intermittent fault that becomes permanent
No communication / Link Error with ABS controller (03) via VAG-COM
Failed state safety/emissions inspection
How to Fix
To confirm that the module is the problem, scan the ABS system with a VAG scan tool (factory scanner or VAG-COM/VCDS) — OBD-II generic scanners will not read ABS codes, and if you get a 'Link Error' / no communication with controller 03 (ABS Brakes), the module is almost certainly the cause. Rather than buying a new unit (largely NLA from Audi), the EBCM can be unbolted from the hydraulic block and sent out for rebuild. Only the electronic part of the ABS pump is normally needed — it is attached to the side of the pump with six torx screws and can be removed by first removing the passenger side front wheel and the inner wheel arch plastic liner, then unbolting the washer bottle and moving it out of the way. Repair services (Module Master, XeMODeX, UpFix, ECU Testing) keep coding/adaptations intact so the rebuilt module is plug-and-play with no programming required.
High ConfidenceLast reported by owners May 2026Reviewed May 2026
On the 1997-2003 Audi A8, the D2 A8's hydraulic system uses Pentosin mineral oil shared between the power steering pump, ZF rack with Servotronic module, and (on non-NA self-leveling cars) the rear shock accumulators. Owners report leaks in the middle of the pump where the two-piece housing is bolted together, often diagnosed with UV dye. Whining on cold start, low fluid in the trunk-mounted reservoir, and visible Pentosin (green) under the engine are classic signs. The dash brake warning light can also illuminate if the Pentosin reservoir is low or the hydraulic brake booster system is low on pressure, since the same fluid feeds the brake servo on these cars.
Common Symptoms
power steering whine on cold start
Pentosin fluid puddles under engine
low fluid in trunk reservoir
heavy steering when fluid is low
brake warning light when reservoir empty
How to Fix
Inspect the ZF tandem pump, rack pinion seal, and high-pressure lines with the engine running. A ZF rebuilt pump is around $280 in parts plus ~$350 labor and typically eliminates cold-start whine. Always refill with Pentosin CHF 11S (green) — never ATF, which destroys seals. When replacing the rack, also replace the Servotronic fluid strainer and o-rings on the nipple. Bleed by raising the front wheels off the ground and briefly starting the engine per Bentley procedure until air clears.
High ConfidenceLast reported by owners May 2026Reviewed May 2026
On the 1997-2003 Audi A8, the 4.2 V8 in the D2 A8 (both the early 32-valve ABZ and the later 40-valve AKB/AUX/AYS/BFM) runs a vacuum-operated secondary air injection system with one combi valve per cylinder head, fed by small-diameter hard plastic vacuum lines that become brittle with heat and crack.
Both banks have their own combi valve, and it is usually the hard vacuum line that goes to them that breaks and causes a vacuum leak and inoperable SAI.
Owners report replacing vacuum hoses and the SAI relay only to have the CEL return, and then having to look at replacing the SAI pump (SAIP), the solenoid on top of the engine, and replacing/cleaning out the combi valves aft of each cylinder head, which involves carbon buildup in the cylinder head ports.
Symptom is a check-engine light shortly after a cold start with P0410 (or banked variants P0491/P0492).
Rough idle for first 30-90 seconds after cold start
Failed emissions/smog test
Pump noise (whining) on cold start
How to Fix
Diagnose by starting the engine cold so the SAI system runs and listening for the vacuum leak, then looking around for the crack.
Sticky/partly opening combi-valve or slow running pump are all candidates — you can spin the pumps up using VCDS
output tests to verify pump current draw. Replace brittle vacuum hose with silicone, test combi valves with a hand vacuum pump (they should hold vacuum and audibly click open), and if codes persist with new vacuum/valves the SAI ports in the head will need to be carbon-cleaned. The pump itself (smog pump) typically fails when a leaking combi valve allows exhaust moisture to back-feed and corrode the impeller.
High ConfidenceLast reported by owners May 2026Reviewed May 2026
NHTSA Recalls5 recalls
POWER TRAIN:AUTOMATIC TRANSMISSION
VOLKSWAGEN IS RECALLING 13,900 MY 1996-2003 AUDI A8 VEHICLES EQUIPPED WITH A 5-SPEED AUTOMATIC TRANSMISSION. THE LOCKING CABLE MAY MOVE OUT OF POSITION OVER TIME. WITH THE LOCKING CABLE OUT OF POSITION, THE SHIFTER CAN BE MOVED OUT OF THE "PARK" POSITION EVEN IF THE IGNITION KEY IS NOT IN THE IGNITION LOCK.
Campaign #08V39700014/08/2008
AIR BAGS:FRONTAL:DRIVER SIDE:INFLATOR MODULE
Volkswagen Group of America, Inc. (VW) is recalling certain 2000-2001 TT Roadster, 2000 TT Coupe, 1999 Audi A8, 1998-2000 Audi A6, and 1999-2000 Audi A4 vehicles equipped with Non-Azide Driver air bag Inflators (NADI) that do not contain phase stabilized ammonium nitrate (PSAN) propellant. Due to a manufacturing issue, the NADI inflators may absorb moisture, possibly causing the air bag to deploy improperly in the event of a crash.
Campaign #20V05600031/01/2020
FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY:FILLER PIPE AND CAP
VEHICLE DESCRIPTION: PASSENGER VEHICLES EQUIPPED WITH A FUEL AND VAPOR LEAK DETECTION SYSTEM. A "BLIND COVER" AT THE FILLER NECK OF THE FUEL TANK MAY NOT SEAL PROPERLY ALLOWING FUEL VAPOR TO ESCAPE.
Campaign #01V25900015/08/2001
STEERING:LINKAGES:ROD:RELAY:CONNECTING
VEHICLE DESCRIPTION: PASSENGER VEHICLES. THE TIE RODS OF THE STEERING ASSEMBLY ARE PROTECTED ON EACH SIDE BY A SEAL TO PREVENT MOISTURE AND DUST PARTICLES FROM ENTERING THE SWIVEL BEARING MECHANISM. IT IS POSSIBLE THAT SOME TIE ROD SEALS MAY NOT SEAL PROPERLY.
Campaign #99V24800013/09/1999
STEERING:LINKAGES:ROD:RELAY:CONNECTING
VEHICLE DESCRIPTION: PASSENGER VEHICLES. THE TIE RODS OF THE STEERING ASSEMBLY ARE PROTECTED ON EACH SIDE BY A SEAL TO PREVENT MOISTURE AND DUST PARTICLES FROM ENTERING THE SWIVEL BEARING MECHANISM. IT IS POSSIBLE THAT SOME TIE ROD SEALS MAY NOT SEAL PROPERLY.
Campaign #00V41400006/12/2000
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According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2003 Audi A8 has 4 documented issues. The most frequently reported are: D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine), Bosch 5.3 ABS Control Module Internal Failure (EBCM), Pentosin CHF11S hydraulic system leaks (power steering pump, rack, hoses). Of these, 2 are rated critical and should be addressed promptly.
Is the Audi A8 reliable?
The 2003 Audi A8 has 4 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 2 issues are rated critical: D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine) and Bosch 5.3 ABS Control Module Internal Failure (EBCM). 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 A8 problems?
Repair costs for known Audi A8 issues range from $80 to $3,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine), typically costs $1,500-$3,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 1997-2003 Audi A8 D2 A8 4.2 V8 Timing Belt — Interval Retroactively Cut from 105k to 75k Miles (Interference Engine)?
The D2 A8 4.2L V8 (both the early 32-valve ABZ and the later 40-valve AUX/AWN/AKB) is an interference engine driven by a rubber timing belt. The original published interval was 105K miles on the C5 and D2 4.2, until Audi retroactively changed it to 75,000 miles. Many original-own… Repairs typically run $1,500-$3,000. Severity: high.
What is the 1997-2003 Audi A8 Bosch 5.3 ABS Control Module Internal Failure (EBCM)?
The Bosch 5.3 ABS/EBCM control module mounted to the side of the hydraulic pump unit suffers from internal solder joint and fine aluminum bond-wire fatigue, causing intermittent then permanent loss of ABS function. The Audi ABS pump & module system has been a very common failure… Repairs typically run $200-$600. Severity: high.
What is the 1997-2003 Audi A8 Pentosin CHF11S hydraulic system leaks (power steering pump, rack, hoses)?
The D2 A8's hydraulic system uses Pentosin mineral oil shared between the power steering pump, ZF rack with Servotronic module, and (on non-NA self-leveling cars) the rear shock accumulators. Owners report leaks in the middle of the pump where the two-piece housing is bolted toge… Repairs typically run $400-$2,500. Severity: medium.
What is the 1997-2003 Audi A8 Secondary Air Injection P0410/P0411 — Cracked Vacuum Lines, Stuck Combi Valves, Carbon-Clogged Head Ports?
The 4.2 V8 in the D2 A8 (both the early 32-valve ABZ and the later 40-valve AKB/AUX/AYS/BFM) runs a vacuum-operated secondary air injection system with one combi valve per cylinder head, fed by small-diameter hard plastic vacuum lines that become brittle with heat and crack.
Both… Repairs typically run $80-$1,400. Severity: medium.
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.
