Audi A4
2.0-litre TDI with 140 PS — unit injector (PD) in the B7 generation. Cleaner combustion than the 1.9 TDI, but PD elements coke up from 120,000 km and can cause power loss. Oil pump drive susceptible to wear up to October 2009.
Worry engine — costly weakness looms
126 hp 2.0L with a known issue: hexagonal oil pump drive shears — engine failure. The risk of expensive repairs overshadows any driving pleasure.
Engine Weaknesses 6
On the 2.0 TDI BVE (model years 2005–2009) the hex drive shaft in the oil pump module shears off. The oil pump fails instantly, usually at high revs — minimum damage is a dead turbo, often total engine failure. Repair costs 4,000–10,000 €.
Symptoms: Oil pressure warning light briefly illuminates (damage already done), engine noises, then engine stops — usually without warning
On the 2.0 TDI BVE camshafts develop deep scoring, often from oil starvation or poor oil quality. Later consequence: metal particles in the oil and total engine failure. Camshaft replacement costs 1,100–3,600 €.
Symptoms: Progressive power loss, rough engine running, metal particles visible in oil, clattering from valve train
The 170hp variant has piezo-controlled PD injectors which fail far more frequently than the simpler variants. Four elements cost around 2,000 € to replace. Ultrasonic cleaning possible from 375 €.
Symptoms: Heavy hesitation, power loss, increased consumption, rough engine running
The cylinder head on the 170hp PD engine is known for cracking. Can lead to coolant/oil mixing. No inexpensive replacement possible as the replacement head shares the same weak point.
Symptoms: White exhaust plume, mayonnaise under the oil filler cap, coolant loss
The EGR system on the 2.0 TDI is prone to carbon deposits on the valve and cooler. Particularly bad in short-trip use. A defective EGR valve costs 300–800 € including fitting.
Symptoms: Rough idle, power loss, engine stumbling, EGR fault code in OBD, increased consumption
The DPF on the BVE permanently blocks on frequent short-trip use. Fuel dilution of the oil during regeneration attempts raises the oil level and thins the oil.
Symptoms: DPF warning light, rising oil level indicator, fuel smell at the dipstick, power loss, limp mode
Vehicle Weaknesses 6
On the 2.0 TDI the hexagonal shaft of the oil pump drive can snap, causing immediate oil pressure loss and engine damage. Preventive replacement is recommended.
Airbags manufactured by Takata can deploy with excess pressure and propel metal fragments. Worldwide recall campaign.
Control arms and tie rod ends wear prematurely. Clunking and rumbling on poor surfaces. The multi-link front axle is maintenance-intensive.
Defective ignition coils can immobilise the engine or cause severe running roughness. Mainly affects 1.8T and 2.0 TFSI engines.
From model year 2004 Audi used partial bonding instead of full galvanisation. Wheel arches and sills are vulnerable to rust, especially on older examples without cavity protection.
Rear wheel bearings fail regularly on the A4 B7. Quattro models show increased wear.