BMW 3 Series E46 (1998-2006): known problems and buying guide

Engines and gearboxes

• 1.9 M43 (M43TÜB19UL, M43TÜB19OL, to 2001): old gaskets leak oil.
• 1.8 and 2.0 N42 (N42B18, N42B20): the timing chain is the main risk.
• 1.8 and 2.0 N46 (N46B18, N46B20, N46B20A): chain wear is seen less often than on the N42.
• 2.0 to 2.8 M52TÜ and 2.2 to 3.0 M54 (M52TÜB20, M52TÜB25, M52TÜB28, M54B22, M54B25, M54B30): oil use is the main risk.
• 2.0 M47 and 3.0 M57 diesels (M47D20, M47D20TÜ, M57D30, M57D30TÜ): swirl flaps are the main risk.
• 5-speed automatic: often lasts 250,000-300,000 km before overhaul.
• xDrive (325xi, 330xi, 330xd): no fault confirmed in the sources read.

In detail

Rear subframe mounts cracking

• Symptoms: a clunk or creak from the rear under acceleration, though many cases are silent.
• Which cars: E46 built 1999 to 2006, per the US class action. Gebrauchtwagenberater names cars delivered until March 2000 as most at risk.
• Fix: a welder repairs the cracks and steel reinforcement plates are welded in. The rear suspension and driveshaft come off.
• Cost: no confirmed price. No European recall is confirmed.

Sources: BMWtuning: E46 subframe cracks, BMWblog: subframe class action, BMW-Syndikat forum: rear axles tearing out, Gebrauchtwagenberater: E46 problems

Takata passenger airbag

• Symptoms: none while driving. In a crash the inflator can rupture and throw metal fragments.
• Cause: the propellant degrades with humidity and heat, according to the US recall texts.
• Fix: the dealer replaces the passenger airbag free of charge.

Sources: BMW-Syndikat forum: airbag recall, NHTSA 20V-018, NHTSA 13V-172

N42 and N46 timing chain

• Symptoms: a rattle or noise on cold start.
• Cause: the original tensioner is too short, so the chain goes slack and wears the guides. Kolesa adds that the plastic guides break with age.
• Fix: a longer, revised tensioner replaces the original. Check that the chain, tensioner and guide rail were all replaced.
• Typical life: Auto.ru puts the N42 chain at about 100,000-150,000 km.

Sources: unixnerd: N42 faults, unixnerd: N46 faults, BMWBLOG: N42 engine guide, Gebrauchtwagenberater: E46 problems, Kolesa: used E46 chassis and engines

M47 and M57 swirl flaps

• Symptoms: unstable running. In the worst case a flap breaks off and falls into the cylinder.
• Cause: carbon build-up (coking) makes the flaps break off.
• Which cars: the M47 318d and 320d, and the M57 330d.
• Fix: Auto.ru says the flaps cannot be repaired on their own; the manifold is replaced as a whole.

Sources: Gebrauchtwagenberater: E46 problems, Auto.ru: E46 faults with mileage

Cooling system plastic parts

• Symptoms: an overheating warning, a leak at the expansion tank or lower hose, and a loud fan.
• Cause: plastic parts. The expansion tank cracks with heat, the water pump impeller breaks, and the thermostat wears out.
• Which cars: the thermostat on all engines; the tank and pump on the sixes (M52TÜ and M54).
• Typical km: the tank at about 120,000-160,000 km, the pump at about 97,000-161,000 km, the thermostat at about 97,000-121,000 km.
• Fix: replace the tank, pump and thermostat together. Kfz-Dietrich advises replacing the tank from about 150,000 km.

Sources: BMWtuning: E46 cooling system, Kfz-Dietrich: youngtimer maintenance

Body rust

• Symptoms: holes at the rear wheel arches, swelling at the strut towers, and rot under the sill trim.
• Cause: moisture and acid vapour from the battery get into the floor niches.
• Check: remove the sill trim and look from outside. Lift the carpet and check the floor under both footwells.

Sources: Kolesa: used E46 with fast rust, Gebrauchtwagenberater: E46 problems

Six-cylinder oil use

• Symptoms: the oil level drops between changes.
• Cause: worn crankcase ventilation parts. On the M54 the KGE valve membrane tears. On the M52TÜ the PCV diaphragm wears out.
• Cost: Kfz-Dietrich gives about 50 EUR for the KGE valve part (Germany, year not stated). Labour not stated.

Sources: Gebrauchtwagenberater: E46 problems, Kfz-Dietrich: youngtimer maintenance

Steering and suspension wear

• Symptoms: play in the steering rack, a whining pump, and leaks at the steering gear.
• Cause: a worn rack, and dirty power steering fluid that damages the seals.
• Typical km: rack play appears at about 20,000-60,000 km, according to Za Rulem. BMW has no adjustment, so dealers replace the rack.

Sources: Kfz-Dietrich: youngtimer maintenance, Za Rulem: E46 fault list

Recalls

In the US, a recall (NHTSA 19V-851, 19V-852, 19V-853) covers the driver airbag on 1999 to 2001 cars; no European recall is confirmed.

Check open campaigns for your VIN with a BMW dealer.

Maintenance

• Cooling: replace the expansion tank from about 150,000 km, and the thermostat housing every 100,000 km.
• Power steering: change the fluid after about 100,000 km. Use Pentosin CHF 11S, never ATF.

Sources

English

• BMWtuning: E46 subframe cracks
• BMWtuning: E46 cooling system problems
• BMWblog: E46 subframe class action
• unixnerd: N42 faults
• unixnerd: N46 faults
• BMWBLOG: N42 engine guide
• NHTSA 13V-172
• NHTSA 19V-851
• NHTSA 19V-852
• NHTSA 19V-853
• NHTSA 20V-018

German

• Gebrauchtwagenberater: BMW 3er E46 problems and buying advice
• Kfz-Dietrich: BMW youngtimer maintenance
• BMW-Syndikat forum: rear axles tearing out
• BMW-Syndikat forum: airbag recall

Russian

• Kolesa: used E46 with fast rust
• Auto.ru: E46 faults with mileage
• Za Rulem: E46 fault list
• Kolesa: used E46 chassis and engines