BMW 2.2i
Successor to the M52 with aluminium crankcase and double VANOS. Very reliable; typical weaknesses are cooling system components and the crankcase ventilation.
Velvet-handed entry-level six
170 hp from the M54 R6 — silky-smooth; without the power-steering pump the Z4 feels noticeably more immediate than the 3 Series. No racing car, but an honest naturally aspirated engine with charm.
Engine Weaknesses 5
The DISA flap in the M54B22 intake manifold can break its shaft. If the flap breaks off and enters the engine, catastrophic damage is likely. The membrane wears regularly. Preventive replacement from 120,000 km is advisable.
Symptoms: Hesitation under acceleration, power loss, whistling noise after engine shutdown, rough idle
The DISA variable intake valve breaks at the shaft base or the membrane tears. Fragments can be sucked into the engine and cause catastrophic damage.
Symptoms: Power loss in the lower rev range, rattling or clattering from the intake area, in the worst case engine damage from ingested fragments.
The crankcase ventilation hoses and the accordion boot to the idle control valve become brittle and crack. Unmetered air bypasses the MAF sensor and overwhelms mixture control. Typical on vehicles over 10–15 years old.
Symptoms: Rough idle, rich/lean mixture deviation, misfires, poor cold-start drivability, engine warning light
Camshaft position sensors (intake and exhaust) on the M54B22 fail with increasing age. Cheap aftermarket parts are frequently poor quality. Use only genuine BMW, Vemo, or Hella sensors.
Symptoms: Power loss of approximately 50 hp, hesitation around 4,000 rpm, poor hot-start behaviour, engine warning light
The rectangular gasket between the oil filter housing and the engine block fails regularly. BMW part number 11421719855 — aftermarket gaskets tend to have a shorter service life.
Symptoms: Oil seeping below the oil filter, oil smell when engine is hot.
Vehicle Weaknesses 7
The hydraulic pump for the Z4 E85 hood is mounted in a poorly protected position. Blocked drains allow water ingress; the pump corrodes and fails. Replacement is labour-intensive and expensive.
The electric power steering on the Z4 E85 occasionally fails — particularly on short-trip drivers as the battery becomes too weak. Steering angle sensor faults and column defects also occur.
The N46B20 four-cylinder in the 2.0i Z4 E85 suffers from premature timing chain wear due to a weak chain tensioner. Neglected oil maintenance causes the chain to elongate and can lead to engine damage.
Water enters through leaking tail lights or the boot vent. The expansion rivets on the tail lights become porous, seals age and allow moisture in. Can lead to short circuits and mould.
Ignition coil failures are a known issue on the Z4 E85, particularly at higher mileage. Oil from the valve cover gasket into the spark plug tubes is often a contributing factor. Multiple coils can fail in succession.
The sporty suspension setup on the Z4 E85 leads to above-average tyre wear, especially at the rear. Rear tyres can be at the wear limit after just 25,000 km. Broken springs have also been reported.
On the E85 Z4, the rain sensor and window regulator motors fail more often than usual. The rain sensor triggers in sunshine; windows move jerkily or not at all — both are age-related symptoms.
Reports & Tests
1161 owner complaints filed with NHTSA (2002–2008). Most reported: Steering (965), Airbags (86), Electrical (52).