Audi A4 — deep research dossier
Published · Researched 2026-09-21
Audi A4 — deep research (September 2026)
What the car is (September 2026)
The B9-generation Audi A4 (facelifted "B9.5" from 2020) — the compact executive sedan Audi retired after the 2025 model year, replacing it with the A5 liftback. Now a used-only car. Core spec: 2.0 TFSI (EA888), 201 hp (40 TFSI) or 261 hp (45 TFSI), 7-speed S tronic, FWD or quattro; S4 gets the 3.0T V6. 5 seats, ~460 L boot. When new, the 2025 A4 started around $43,000 in the US (UNVERIFIED exact). China got the long-wheelbase A4L (FAW-VW). Notable: the A4 badge will return as an EV under Audi's even-number naming logic — the combustion car is done.
Social-first owner evidence (primary layer)
Tier 2 — strong forum signal (AudiWorld B9 community is deep and technical); social.search across Threads/IG/Facebook failed on infrastructure.
- AudiWorld B9 forum, senior member (Apr 2025, "Considering a used B9"): "The B9 A4 generally gets very high reliability ratings. Check Consumer Reports... Water pump / thermostat leaks are an issue in the early B9 cars... The 2020 has the IHI turbocharger which has incurred failures with a loose wastegate. 2021+ cars have a Garrett turbo assembly which so far seems to be immune to the problem. High oil consumption and timing chain issues have not emerged as issues on these cars unlike the B8." On electronics: "Troll the Audi related forums and electronic / electric weirdness is a not an uncommon issue... electronic systems are the highest contributor to unreliability on the A4 (like just about all high end cars)."
- AudiWorld member (2018 car): "It is good to hear from so many that the B9 appears thus far to be devoid of any major issues (other than the water pump/thermostat housing issue that is well documented)." Caution: "it still too early in the B9's life cycle to pronounce it dead nuts reliable... the measure of whether a car is 'reliable' is to be taken over the long haul — what has the thing been like for 7 years/85,000+ miles?"
- What Car? Reliability Survey: A4 ranked 15th of 23 executive cars, 90.1% — ahead of the C-Class and Superb petrol, behind the 3 Series and XE. Owners: "many owners of both petrol and diesel models report a trouble-free experience," but engine faults (oil consumption on 2.0 TFSI, water pump leaks), electrical glitches, ABS pump failures, and S tronic "lurches" are the recurring themes. Dealer network praised; repair costs "predictably premium."
- carsfrenzy (2023 Allroad, same family): "Depreciation from new MSRP has been substantial — often around one-third off by the mid-2020s — which is why the used market is where this car makes the most sense."
Reliability record
Above average for the class — the B9.5 is the reliability sweet spot of the modern A4 line. Documented watch items: water pump/thermostat housing leaks (mostly early B9 cars), IHI turbo wastegate failures on 2020 cars (fixed by the 2021+ Garrett turbo), oil consumption on some 2.0 TFSI units, S tronic low-speed lurches, electrical/electronic weirdness (the biggest CR complaint category), and occasional ABS pump failures. No catastrophic engine pattern like the B8 generation's oil/timing-chain disasters. Recalls: rear-axle alignment campaign (2021, ~10k cars), passenger occupant-sensor recall (2023 models); check VIN.
Support reality
Strong while it lasted — and it will last: the A4 shares the EA888/S tronic hardware with millions of VW-group cars, so parts and independent specialist knowledge are abundant and cheap by premium standards. Audi dealers still service it. The A5 replacement shares the new PPC platform, so dealer attention is shifting, but the B9's parts commonality insulates owners.
Hype flags
None. The A4 died quietly — no farewell hype, no "future classic" campaign. Enthusiast forums treat it as the sensible used buy, which is exactly what it is. The only marketing-adjacent noise is Audi's A5 launch positioning, which implicitly frames the A4 as the old car.
Model-year timeline 2021–2026
| Year | Generation / facelift | Powertrain / battery / motor changes | Reliability notes | Recalls / TSBs | Used price band | | 2021 | B9.5 facelift (mature) | 2.0 TFSI with Garrett turbo (wastegate issue resolved); 12V mild hybrid added | Strong year per forums | Rear-axle alignment campaign | UNVERIFIED | | 2022 | B9.5 | Same | Strong | Occupant-sensor (2023 MY overlap) | UNVERIFIED | | 2023 | B9.5 | Same | Strong | Passenger occupant-classification sensor | UNVERIFIED | | 2024 | B9.5 | Same | Strong | — | UNVERIFIED | | 2025 | Final year; replaced by A5 liftback | Same | Strong; last of the line | — | UNVERIFIED | | 2026 | — | Not sold (badge retired; A5 takes over) | — | — | — |
Sweet-spot year: 2021–2022 — facelift-mature cars with the Garrett turbo (no IHI wastegate failures), past the early water-pump era, and deep into the depreciation curve (roughly a third off MSRP). Years to skip: 2017–2020 — early B9 water pump/thermostat leaks and the 2020-only IHI turbo wastegate failures. (Pre-2021, but the key skip guidance for this model.)
Raw quotes
- AudiWorld senior member: "The B9 A4 generally gets very high reliability ratings... The 2020 has the IHI turbocharger which has incurred failures with a loose wastegate. 2021+ cars have a Garrett turbo assembly which so far seems to be immune to the problem."
- AudiWorld senior member: "High oil consumption and timing chain issues have not emerged as issues on these cars unlike the B8."
- AudiWorld member: "the measure of whether a car is 'reliable' is to be taken over the long haul — what has the thing been like for 7 years/85,000+ miles?"
- What Car? owners: "keeping a close eye on coolant levels and oil usage is highly recommended."
- What Car?: A4 "ranked 15th out of 23 cars in the executive car class... more reliable than the... Mercedes C-Class."