PeachStamp
All model research

Audi RS4 (B7) 4.2 FSI V8buyer's guide

2006–2008

The faults this model is known for, what they tend to cost in the UK, and what a service history has to show before any of them counts as covered. Researched from the sources shown, and open to correction.

If none of it were documented

£6,100–£15,200

Across 8 costed items.

This is a ceiling, not a forecast. A report on a specific car counts only the items its paperwork does not already cover - a folder showing the clutch done last year removes that line entirely.

Known faults

Carbon build-up on the intake valves

£500–£1,000

Direct injection sprays fuel into the cylinder rather than past the valve, so nothing washes the back of the intake valve and deposits accumulate. The car loses crispness, idles unevenly and eventually misfires. It is not a defect so much as a consequence of the injection system, which means it is scheduled work rather than bad luck, and a car with no record of it having been done has it building up.

The inlet manifold comes off and all eight ports are cleaned by hand, reported from around £500 upwards in the UK because it is slow work rather than difficult work.

Typically bites

Commonly quoted at roughly every 40,000 miles. An undocumented car past that is the question.

Verified against 3 published sources.

DRC (Dynamic Ride Control) units

£900–£2,500

The hydraulically linked damping system leaks, and once it does the car sits unevenly and rides badly. It is among the most commonly cited faults on the model. Owners either replace the units with the same system or convert to conventional coilovers, and the two routes cost very different amounts, so an invoice saying which was done matters as much as one saying it was done.

Replacing like for like is the expensive route and runs into four figures. A conversion to conventional dampers is a common alternative and changes the character of the car, which is a thing a buyer should know before rather than after.

Typically bites

Age- and use-driven. Most surviving cars have had this addressed one way or the other, and a car that has not is sitting on it.

Verified against 2 published sources.

Oil cooler and cooling system leaks

£500–£1,500

The oil cooler leaks or clogs, and a high-revving V8 that loses its ability to shed heat does not stay a cooling problem for long. The related pipework and seals age at the same rate, so this is usually found as a group rather than as one part.

Independent specialist work in the mid hundreds to low thousands depending on how much of the system is replaced at once.

Typically bites

Age-driven rather than mileage-driven.

Verified against 1 published source.

Clutch and dual mass flywheel

£1,200–£2,200

A manual-only car with 420bhp and an eight thousand rpm limit, often driven the way that invites. The flywheel goes with the clutch on these because the labour is the same and replacing one without the other is a false economy every specialist will point out.

Clutch and flywheel together at an independent is a four-figure job, with the parts a meaningful share of it.

Typically bites

Use-driven rather than age-driven, and heavily dependent on how the car has been driven.

Verified against 2 published sources.

Inlet manifold flap screws

£400–£1,200

The screws retaining the inlet manifold flaps work loose, and a loose screw or flap can be drawn into a cylinder. That turns a small fastener into a rebuild, which is why it is the one item on this car worth checking preventatively rather than waiting for a symptom. Early signs are a rough idle, lost power and a warning light, by which point the flap has usually already moved.

Inspecting and securing the flaps is a modest specialist job. An ingested flap is an engine strip and is in a different category entirely.

Typically bites

Not tied to a mileage. It is a fastener that either has been checked or has not.

Verified against 2 published sources.

Connecting rod bearings

£1,500–£3,000

The 4.2 V8 wears rod bearings prematurely when it is worked before reaching temperature or when oil intervals are stretched. Less famous than the equivalent on the BMW engines of the era and driven by the same two things, which makes the oil history in the folder directly relevant rather than merely reassuring.

A four-figure specialist job done preventatively. A spun bearing is an engine.

Typically bites

Driven by how the car has been used and serviced rather than by a mileage. Cold starts driven hard are the pattern implicated.

Verified against 1 published source.

High pressure fuel pump and its camshaft lobe

£600–£2,000

The high-pressure pump is driven off a camshaft lobe, and both the pump and the lobe wear. The symptom is fuelling that falls short in the low and mid range rather than a dramatic failure, so it is easy to attribute to the car simply feeling flat.

Pump replacement is a specialist job in the mid hundreds to low four figures. Lobe wear means the camshaft, which is considerably more.

Typically bites

Mileage-driven, and reported alongside the general oil leak era of these cars.

Verified against 1 published source.

Camshaft and rear main seal oil leaks

£500–£1,800

The seals harden and weep, and it is described as very common on higher-mileage cars. The rear main is the expensive one, not because the part is dear but because the gearbox comes out, which is the same access a clutch needs. A car having its clutch done is the moment to address it, and a clutch invoice that does not mention it is a missed opportunity.

Cam seals are moderate. The rear main is a four-figure job on its own and close to free alongside a clutch.

Typically bites

Commonly reported between 70,000 and 120,000 miles.

Verified against 1 published source.

Service interval

Every 9,000 miles or 12 months, whichever comes first.

Specialists work to a shorter oil interval than the factory schedule on the 4.2 FSI. The carbon cleaning cycle sits alongside it at roughly every 40,000 miles and is the item most often missing from an otherwise thick folder.

The interval is here so a report can do arithmetic rather than form an opinion: last recorded service, current mileage, today's date. Whether a car is overdue is a sum, and sums should not be able to hallucinate.

What to check on the day

Written to be read standing next to the car, with the folder open.

  1. Ask when the intake valves were last cleaned. A seller who has owned it a while and has never heard of the job has not had it done.

  2. Look at the car standing still on level ground and check it sits evenly. Uneven ride height is the DRC.

  3. Drive it over a poor surface and feel for a corner that crashes rather than absorbs.

  4. Do not ask for timing chain history. It is the S4 that has that problem, and asking marks you out as someone who has read the wrong guide.

  5. Listen for an uneven idle and feel for hesitation low in the rev range, both of which point at carbon.

What this research does not know

  • The timing chain exclusion is stated by specialists and enthusiast guides rather than by a manufacturer bulletin. It is included because the misconception is widespread enough to change what a buyer asks for.
  • DRC costs vary enormously between a like-for-like replacement and a coilover conversion. The band spans both routes rather than describing one.
  • Carbon cleaning is quoted from UK sources at "£500 upwards", which is a floor rather than a range. The upper figure here is inferred and flagged.
  • A PCV valve fault described in several search results was deliberately excluded. The symptoms quoted are boost pressure loss, and the B7 RS4 is naturally aspirated - that material belongs to the supercharged B8 RS4 or the 2.0T A4 of the same body. It is noted here because the mix-up is easy to make and the result would have been a costed liability on a part behaving in a way this car cannot.

Last reviewed on 22 August 2026. Cost bands are indicative UK independent-specialist rates, not quotes.

Now find out which of these the car you're looking at can actually prove.

Photograph or upload the seller's folder and every invoice is read, checked against the official mileage record, and matched against the list above - so the total you get is what this car has no evidence for, not what the model might cost in general.

See a full worked exampleLook up a registration