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Audi · Mid-Size · 2005–2009 Custom Search

Audi RS4 B7

Weaknesses, engine ratings and buying advice

★★★★★
1.0 / 5.0 · Based on 1 engine variants · How we rate

Body Variants

The Audi RS4 B7 is available as Sedan and Avant and Convertible — choose your body type for specific insurance data:

Generations

Engine Overview

The Audi RS4 B7 is available with one engine variant at 420 hp.

RS4 · Petrol· 420 PS
2005 2009

The BNS is a high-revving V8 with 420 PS at 7,800 rpm and an 8,250 rpm redline — piston speed at rated rpm: 25.4 m/s, identical to a 2012 F1 engine. FSI direct injection without port injection leads to the most aggressive carbon build-up of all 4.2 FSI variants: according to specialist workshops, no RS4 B7 reaches its rated power on the dyno — measured outputs were 347 to 385 PS instead of 420. Mechanical intake cleaning (BEDI) every 15,000–20,000 km restores power, chemical cleaning is not sufficient. Oil cooler connections corrode through galvanic corrosion (aluminium against steel) and are almost always seized at 15+ years of vehicle age. Water-cooled alternator costs four figures to replace. Oil changes every 10,000 km with 5W-40; at high oil consumption use 15W-50. Compression ratio 12.5:1 requires Super Plus fuel.

  • !! Intake valve coking — no RS4 B7 ever reaches stock power from 30,000 km

    The main problem of the BNS: FSI without port injection heavily cokes the intake valves. Specialist workshops measure 347–385 hp instead of the stock 420 hp. Mechanical BEDI cleaning every 15,000–20,000 km needed; chemical cleaning is insufficient.

    Symptoms: Gradual power loss over months, rough idle, increased fuel consumption, sluggish throttle response in the upper rev range. Often only measurable on a dyno.
    850–1,200 $
    Ad BEDI cleaning RS4 B7intake manifold BNS 4.2 FSIWalnut Blasting RS4
  • !! Timing chain on gearbox side — engine-gearbox separation required from 120,000 km

    The timing chain sits on the gearbox side. Guide rails and tensioners wear; replacement requires engine-gearbox separation. With consistent oil changes (max. 10,000 km) the chain lasts significantly longer. Cold-start rattling is the warning sign.

    Symptoms: Rattling on cold start that disappears after warm-up. At advanced wear, permanent chain rattling and engine warning light.
    4,000–8,000 $
    Ad timing chain BNS RS4 B7chain tensioner 4.2 FSI V8Gleitschiene BNS
  • !! Camshaft adjusters wear with neglected oil maintenance from 90,000 km

    Four camshaft adjusters wear from oil-deficiency-related abrasion. Oil quality and short change intervals (max. 10,000 km) are critical. Rattling on cold start and fault codes are typical signs.

    Symptoms: Rattling on cold start in the camshaft area, power loss at low rpm, engine warning light with camshaft fault codes.
    1,500–3,500 $
    Ad camshaftnversteller BNS RS4079109088J camshaftnversteller 4.2

+ 5 more engine weaknesses + vehicle weaknesses

Vehicle Weaknesses

WeaknessCost
✖DRC suspension dampers leaking

The Dynamic Ride Control hydraulic suspension operating at ~15 bar system pressure is known for leaking dampers. If one damper fails, the others wear faster. Repair requires dealer-level special tooling.

Symptoms: Harder ride, uneven handling, oil marks under the vehicle, knocking dampers
from 80,000 km
Ad DRC damper Audi RS4 B7shock absorber RS4 B7 Dynamic Ride Controlspringungssystem RS4 B7 hydraulisch
 High
!Control arm ball joints worn

Worn control arms are the most common MOT failure on the S4 B7. Ball joints and track rod ends suffer under the heavy vehicle weight and spirited use.

Symptoms: Knocking over bumps, steering flutter, uneven tyre wear
from 120,000 km
Ad control arm Audi S4 B7 complete frontKugelgelenk A4 B7 8Etie rod end S4 B7
 Medium
!Propshaft centre bearing defective

On quattro models the propshaft centre bearing can cause problems and produce a dull knocking noise, especially when accelerating. Typical wear damage at higher mileage.

Symptoms: Dull knocking from the underbody when accelerating, drivetrain vibrations, noises in corners
from 120,000 km
Ad prop shaft center bearing Audi S4 B7prop shaft A4 B7 quattroGelenklager prop shaft A4 B7
 Medium
!Upper front control arms worn

The upper front control arms can fail at higher mileage and are expensive to source. Typical wear pattern on sportily driven examples.

Symptoms: Knocking from the front-wheel area, uneven tyre wear, toe changes
from 100,000 km
Ad control arm oben Audi RS4 B7Dreieckslenker front RS4 B7Lenker front axle A4 B7 quattro
 Medium
●Front and rear wheel bearings

Wheel bearings wear on the RS4 B7 due to the high forces of the quattro drivetrain combined with spirited driving. At high mileage one or more wheel bearings require replacement.

Symptoms: Humming or droning at certain speeds, noise changes during lane changes
from 120,000 km
Ad wheel bearing Audi RS4 B7 frontwheel bearingsatz A4 B7 quattrowheel hubnlager RS4
 Low
NHTSA Owner Complaints
Above average
3 complaints · 2005–2009
  1. 01 Engine & Cooling
    1
  2. 02 Other
    1
  3. 03 Suspension
    1

Top Reported Issues

⚠ Engine & Cooling (1 complaints)
⚠ Other (1 complaints)
⚠ Suspension (1 complaints)
Source: NHTSA (nhtsa.gov) · 2026-03
NHTSA Owner Complaints
Below average
106 complaints · 2004–2008
  1. 01 Lighting
    58
  2. 02 Engine & Cooling
    15
  3. 03 Airbags
    15 ⚠ 2
  4. 04 Electrical
    11 ⚠ 1
  5. 05 Powertrain
    7

Top Reported Issues

⚠ Lighting (58 complaints)
⚠ Engine & Cooling (15 complaints)
⚠ Airbags (15 complaints)
Source: NHTSA (nhtsa.gov) · 2026-03

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Known Problems and Issues +

A total of 19 weaknesses have been documented for the Audi RS4 B7 (2005–2009) — 8 engine-related and 11 vehicle-related. One problem engine: BNS (4.2L FSI V8). Typical issues affect Suspension, Brakes, Electronics, Rust.

What to watch out for with the Audi RS4? See the detailed listing of all engine and vehicle weaknesses in the sections above.

Frequently Asked Questions

What problems and weaknesses does the Audi RS4 B7 have? +
The Audi RS4 B7 has 8 known engine weaknesses and 11 vehicle weaknesses.
What should I look for when buying a used Audi RS4 B7? +
faq.watch_a_avoid
Which engine is recommended? +
None of the available engines are rated 'Good Choice'. Stay away! The most fun to drive is the BNS (4.2L FSI V8). Problem engine: BNS (4.2L FSI V8) — stay away!
Which Audi RS4 B7 engine is the most fun? +
The {code} ({displacement}) offers the most driving fun in the Audi RS4 B7 — rated: "Legendary!". {description} High-revving V8 to 8,250 rpm, six-speed manual, quattro. This combination will never exist again. The B7 is the only RS4 purists take seriously. Sounds like a small Ferrari, lasts like an Audi. Prices climbing double digits annually.
Is the Audi RS4 B7 worth buying used? +
Caution is advised with the Audi RS4 B7 — 1 of 1 engine variants are rated 'Stay Away!'. The engine choice is crucial.
What horsepower variants are available for the Audi RS4 B7? +
The Audi RS4 B7 is available with engine variants from 420 to 420 hp. Petrol: BNS (4.2L FSI V8).

Last updated: February 2026 · All information without guarantee