Audi S4 B9
Weaknesses, engine ratings and buying advice
354 PS
S4 · Benzin
354 hp company car — objectively fast, subjectively empty
Fun to Drive!Body Variants
The Audi S4 B9 is available as Sedan and Avant — choose your body type for specific insurance data:
Generations
Engine Overview
The Audi S4 B9 is available with 4 engine variants — from 340 to 354 hp. 2 variants had engine changes — the model year is crucial.
The first diesel with an S badge in history — and that is not a marketing claim, it is a technical statement. The EA897 evo delivers 700 Nm across a wide band, and the electric compressor (EAV) closes the gap between throttle input and turbo boost build-up in under 250 milliseconds. The result is a diesel with no perceptible turbo lag — when powering out of corners or overtaking, the engine responds immediately because the EAV is already compressing air with up to 7 kW before the exhaust turbo gets up to speed. The 48V system carries not just the EAV but also the belt starter-generator for recuperation and coasting. On the maintenance side: camshaft fractures are the known catastrophic failure pattern of this EA897 generation. Check service history carefully before purchase and ask for evidence of completed TPI measures. Oil pressure drop at idle is by design due to the electronically controlled oil pump — not a fault, but worth noting if it shows up under load.
- !! Low oil pressure from variable oil pump from 150,000 km
The ECU-controlled oil pump reduces pressure at idle to approx. 1.0–1.4 bar. At high motorway oil temperatures with bearing wear, this pressure is insufficient — con-rod bearings seize from 150,000 km.
Symptoms: Oil pressure warning at idle or on country roads, knocking noises, in severe cases engine failure - !! Camshaft breakage (material defect) from 80,000 km
All 272-hp variants built before January 2017 contained faulty camshafts. Tooth flank noise and fractures are possible; Audi acknowledges the problem, goodwill depends on mileage.
Symptoms: Clattering or ticking from camshafts even after brief warm-up, rough running, in severe cases sudden engine stall - !! Timing chain drive worn (4-chain system) from 160,000 km
The EA897 uses four timing chains — one per cylinder bank, one connecting chain and one for the oil pump. All chains, tensioners and guides must be renewed together.
Symptoms: Rattling on cold start, metallic knock on throttle, engine light with camshaft faults
+ 2 more engine weaknesses + vehicle weaknesses
Revised EA897 with improved emissions treatment — three catalysts (oxidation cat, particulate filter with SCR coating, second SCR catalyst) reduce real-world NOx by over 90 percent. The electric compressor (EAV) responds even faster than on the predecessor: under 250 milliseconds to full boost, 700 Nm already on tap at 1,750 rpm. Technical detail: the revised EAV is now water-cooled and spins up to 90,000 rpm — significantly higher than the predecessor. The 48V BSG recuperates up to 8 kW and enables genuine engine-off coasting. Camshaft fractures remain the known major failure pattern for this engine family — check service history before purchase, request TPI documentation. The four-chain camshaft drive is maintenance-intensive; longlife intervals are not recommended at this mileage. If diesel is your thing and turbo lag is your enemy, this is one of the most convincing solutions the market has ever produced.
- !! Timing chain wear and tensioner failure from 80,000 km
The V6 3.0 TDI has four timing chains that wear prematurely with poor maintenance. Rattling on cold start is the typical warning. Complete chain drive replacement costs approx. €3,000.
Symptoms: Rattling or clattering noises on cold start, timing chain warning in instrument cluster - !! Camshaft fracture due to material defect from 90,000 km
On EA897 EVO engines with certain serial numbers (CRT 000001–073951), camshafts can break due to material defects. A break inevitably causes severe engine damage.
Symptoms: Sudden loss of power, rough running, engine stall without prior warning - !! Coolant loss from defective control valves from 90,000 km
Faulty plastic coolant control valves cause coolant loss. The plastic welded joint becomes porous and leaks. Repair costs are around €1,200–1,400.
Symptoms: Dropping coolant level, rising temperature, coolant loss without visible external leak
+ 3 more engine weaknesses + vehicle weaknesses
The first diesel with an S badge in history — and that is not a marketing claim, it is a technical statement. The EA897 evo delivers 700 Nm across a wide band, and the electric compressor (EAV) closes the gap between throttle input and turbo boost build-up in under 250 milliseconds. The result is a diesel with no perceptible turbo lag — when powering out of corners or overtaking, the engine responds immediately because the EAV is already compressing air with up to 7 kW before the exhaust turbo gets up to speed. The 48V system carries not just the EAV but also the belt starter-generator for recuperation and coasting. On the maintenance side: camshaft fractures are the known catastrophic failure pattern of this EA897 generation. Check service history carefully before purchase and ask for evidence of completed TPI measures. Oil pressure drop at idle is by design due to the electronically controlled oil pump — not a fault, but worth noting if it shows up under load.
- !! Low oil pressure from variable oil pump from 150,000 km
The ECU-controlled oil pump reduces pressure at idle to approx. 1.0–1.4 bar. At high motorway oil temperatures with bearing wear, this pressure is insufficient — con-rod bearings seize from 150,000 km.
Symptoms: Oil pressure warning at idle or on country roads, knocking noises, in severe cases engine failure - !! Camshaft breakage (material defect) from 80,000 km
All 272-hp variants built before January 2017 contained faulty camshafts. Tooth flank noise and fractures are possible; Audi acknowledges the problem, goodwill depends on mileage.
Symptoms: Clattering or ticking from camshafts even after brief warm-up, rough running, in severe cases sudden engine stall - !! Timing chain drive worn (4-chain system) from 160,000 km
The EA897 uses four timing chains — one per cylinder bank, one connecting chain and one for the oil pump. All chains, tensioners and guides must be renewed together.
Symptoms: Rattling on cold start, metallic knock on throttle, engine light with camshaft faults
+ 2 more engine weaknesses + vehicle weaknesses
Revised EA897 with improved emissions treatment — three catalysts (oxidation cat, particulate filter with SCR coating, second SCR catalyst) reduce real-world NOx by over 90 percent. The electric compressor (EAV) responds even faster than on the predecessor: under 250 milliseconds to full boost, 700 Nm already on tap at 1,750 rpm. Technical detail: the revised EAV is now water-cooled and spins up to 90,000 rpm — significantly higher than the predecessor. The 48V BSG recuperates up to 8 kW and enables genuine engine-off coasting. Camshaft fractures remain the known major failure pattern for this engine family — check service history before purchase, request TPI documentation. The four-chain camshaft drive is maintenance-intensive; longlife intervals are not recommended at this mileage. If diesel is your thing and turbo lag is your enemy, this is one of the most convincing solutions the market has ever produced.
- !! Timing chain wear and tensioner failure from 80,000 km
The V6 3.0 TDI has four timing chains that wear prematurely with poor maintenance. Rattling on cold start is the typical warning. Complete chain drive replacement costs approx. €3,000.
Symptoms: Rattling or clattering noises on cold start, timing chain warning in instrument cluster - !! Camshaft fracture due to material defect from 90,000 km
On EA897 EVO engines with certain serial numbers (CRT 000001–073951), camshafts can break due to material defects. A break inevitably causes severe engine damage.
Symptoms: Sudden loss of power, rough running, engine stall without prior warning - !! Coolant loss from defective control valves from 90,000 km
Faulty plastic coolant control valves cause coolant loss. The plastic welded joint becomes porous and leaks. Repair costs are around €1,200–1,400.
Symptoms: Dropping coolant level, rising temperature, coolant loss without visible external leak
+ 3 more engine weaknesses + vehicle weaknesses
With the B9 generation Audi swapped the supercharger for a twin-scroll turbo — and built in a character compromise. The EA839 runs the Miller cycle with late intake valve closing and 11.2:1 compression, making it more efficient on paper than its predecessor. In practice: a broader rev band (500 Nm from 1,300 to 4,500 rpm), but the immediate supercharger feel is gone. The turbo sits in the hot-V between the cylinder banks — keeping the engine bay compact, but demanding thermally. Known weak points: the oil filter housing in the hot section tends to leak, and the thermostat shares its housing with the water pump — if one fails, both usually get replaced. Misfire on cylinder 6 starts appearing around 100,000 km, often from aged spark plugs or faulty ignition coils. The timing chain sits on the engine side, not the gearbox side — a genuine advantage over some contemporaries.
- !! Rocker Arm Roller Failure (GP0 Production)
Early CWGD units with P-code GP0 (up to production date 06.08.2018) have poor-quality rocker arm rollers. The small bearing rollers can fall out and end up in the oil sump — camshaft and piston damage possible.
Symptoms: Combustion misfire, engine fault light, rough running, clattering noise from cylinder head. - !! Water Pump Internal Failure with Coolant in Vacuum System from 80,000 km
The EA839 water pump is vacuum-controlled. On internal failure, coolant enters the vacuum system and spreads to further engine components. The old 4-bolt pulley is the prime suspect — identifiable if original pump still fitted.
Symptoms: Coolant warning light, coolant loss without external leakage, P0299 (boost pressure too low), 'drivetrain fault', 12V battery no longer charging. - !! 48V Mild Hybrid System Fault (from 2019 Facelift)
The belt starter-generator (BSG) and the 48V battery can fail, especially on vehicles before 2021 without the protective cover over the control unit. Diagnosis and calibration required after replacement.
Symptoms: '48V system fault' in display, start-stop disabled, no recuperation, rough or delayed starting, limp mode.
+ 5 more engine weaknesses + vehicle weaknesses
With the B9 generation Audi swapped the supercharger for a twin-scroll turbo — and built in a character compromise. The EA839 runs the Miller cycle with late intake valve closing and 11.2:1 compression, making it more efficient on paper than its predecessor. In practice: a broader rev band (500 Nm from 1,300 to 4,500 rpm), but the immediate supercharger feel is gone. The turbo sits in the hot-V between the cylinder banks — keeping the engine bay compact, but demanding thermally. Known weak points: the oil filter housing in the hot section tends to leak, and the thermostat shares its housing with the water pump — if one fails, both usually get replaced. Misfire on cylinder 6 starts appearing around 100,000 km, often from aged spark plugs or faulty ignition coils. The timing chain sits on the engine side, not the gearbox side — a genuine advantage over some contemporaries.
- !! Rocker Arm Roller Failure (GP0 Production)
Early CWGD units with P-code GP0 (up to production date 06.08.2018) have poor-quality rocker arm rollers. The small bearing rollers can fall out and end up in the oil sump — camshaft and piston damage possible.
Symptoms: Combustion misfire, engine fault light, rough running, clattering noise from cylinder head. - !! Water Pump Internal Failure with Coolant in Vacuum System from 80,000 km
The EA839 water pump is vacuum-controlled. On internal failure, coolant enters the vacuum system and spreads to further engine components. The old 4-bolt pulley is the prime suspect — identifiable if original pump still fitted.
Symptoms: Coolant warning light, coolant loss without external leakage, P0299 (boost pressure too low), 'drivetrain fault', 12V battery no longer charging. - !! 48V Mild Hybrid System Fault (from 2019 Facelift)
The belt starter-generator (BSG) and the 48V battery can fail, especially on vehicles before 2021 without the protective cover over the control unit. Diagnosis and calibration required after replacement.
Symptoms: '48V system fault' in display, start-stop disabled, no recuperation, rough or delayed starting, limp mode.
+ 5 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Recall: Rear Axle Stress Corrosion Cracking (42L1/42L5) Recall 42L1/42L5: Stress corrosion cracking in the rear trailing arm can increase play. Affected: build years 2019–2021. Missing wheel alignment after the initial recall caused severe rear tyre wear. Symptoms: Heavy uneven tyre wear at the rear, air loss from rear tyres in advanced cases | Low | |
| Recall: Seat Heater Wiring — Front Passenger Airbag Deactivated (74E3) Recall 74E3 for S4 B9 (build years 2018–2020): a seat heater wiring fault can cause an occupancy sensor error and deactivate the front passenger airbag. | Low |
Top Reported Issues
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Known Problems and Issues +
A total of 34 weaknesses have been documented for the Audi S4 B9 (2016–2024) — 19 engine-related and 15 vehicle-related. Typical issues affect Other, Electronics, Suspension, Brakes.
S4 (CWGD, 2016–2018) — Be Careful: Rocker Arm Roller Failure (GP0 Production), Water Pump Internal Failure with Coolant in Vacuum System, 48V Mild Hybrid System Fault (from 2019 Facelift). Power: 354 PS.
S4 (DTPA, 2019–2024) — Be Careful: Low oil pressure from variable oil pump, Camshaft breakage (material defect), Timing chain drive worn (4-chain system). Power: 341–347 PS.
S4 (DTNS, 2019–2024) — Be Careful: Timing chain wear and tensioner failure, Camshaft fracture due to material defect, Coolant loss from defective control valves. Power: 341–347 PS.
What to watch out for with the Audi S4? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the Audi S4 B9 have? +
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Last updated: February 2026 · All information without guarantee