BMW 320i N46

The BMW 320i N46 has a reliability score of 48/100, rated "RISKY". Budget buy, expensive surprises lurk inside

The most frequently reported issues are Timing Chain Stretch & Guide Failure, Valve Stem Seal & Oil Consumption, Valve Cover Gasket Oil Leak, Low Oil Pressure / Oil Pressure Sensor Faults, among others. See the Known Issues section above for symptoms, affected mileage, and repair costs.

Yes, this is a documented issue on the N46, typically appearing around 80,000-180,000 km. The N46 is documented to suffer from timing chain guide splitting and chain stretch, most commonly reported after 120,000-150,000 km. Real-world owner reports document actual internal damage from chain jump events (bent valves, broken rocker arms), so despite some online claims that the N46 is a 'non-interference' design, treat a chain failure as a genuine risk of internal engine damage rather than assuming it's a safe, cheap fix. Left unaddressed, catastrophic engine failure is possible. Typical repair cost: €1,500-3,500. DIY difficulty: Expert.

Yes, this is a documented issue on the N46, typically appearing around 100,000-200,000 km. N46 engines are known for hardened valve stem seals leading to oil burning and blue smoke, particularly after cold starts or extended idling. This is independently corroborated: multiple sources cite oil ring/piston ring wear compounding the valve stem seal issue at similar mileages, sometimes requiring piston replacement if seals alone don't resolve consumption. Typical repair cost: €800-2,500. DIY difficulty: Expert.

Yes, this is a documented issue on the N46, typically appearing around 60,000-150,000 km. Valve cover gasket leaks are commonly reported on the N46. Independent sources cite this as occurring roughly every 50,000 km if not addressed. Oil can seep onto hot engine components and create burning smells or fire risk if neglected. Typical repair cost: €150-400. DIY difficulty: Moderate.

Yes, this is a documented issue on the N46, typically appearing around 80,000-160,000 km. Sporadic low oil pressure at idle on the N46B20 is reported, sometimes linked to a faulty oil pressure sensor or switch, but also to genuine internal wear. Typical repair cost: €100-600. DIY difficulty: Moderate.

Yes, this is a documented issue on the N46, typically appearing around 80,000-150,000 km. Faulty lambda sensors are a generic wear item reported on N46 engines. Typical repair cost: €80-300. DIY difficulty: Moderate.

Yes, this is a documented issue on the N46, typically appearing around 100,000-200,000 km. N46 engines can develop crankcase overpressure from a PCV/breather membrane that breaks down over time, increasing oil consumption and causing mixture-related fault codes. Typical repair cost: €50-250. DIY difficulty: Low.

The BMW N46 320i is a driver's car at heart but carries real mechanical risk, particularly around the timing chain and valve stem seals, both of which can become expensive if ignored. Only buy a well-documented example with consistent short-interval oil change history and no cold-start rattles whatsoever. Budget 1,500-3,000 euros upfront for preventative timing chain work if the car has no proof of prior replacement above 100,000 km. Note that post-September 2007 European-market cars got a more powerful 170hp tune of this engine versus the earlier 150hp version, worth confirming which one you're looking at, though this does not change the underlying chain design or risk. This engine rewards attentive ownership but will punish neglect quickly and expensively.

Do not choose between the 150hp and 170hp N46 tunes based on chain reliability, since both share the same timing chain, guide, and tensioner design and neither has a documented fix that reduces chain risk. The 170hp post-2007 tune is a genuine power increase for European cars, worth confirming for performance and tax-band reasons, but treat every N46 the same way at purchase: demand documented short-interval oil changes, a clean cold-start with no chain rattle, and proof of chain replacement if the car is over 100,000 km with no history. Age and service history matter far more here than which power figure is stamped on the V5.

Before buying, check: Cold-start the engine and listen carefully for any chain rattle or knocking in the first 10-30 seconds, walk away if heard; Request full service history showing oil changes no longer than every 10,000 km; reject any car with 30,000 km intervals; Perform or request an OBD scan using INPA or ISTA for live lambda data, timing faults, and valvetronic fault codes; Inspect the top of the engine and valve cover area visually for oil seepage or burnt oil residue indicating gasket leaks; Check the oil cap for excessive crankcase pressure (strong blow when removed) and inspect the dipstick for milky oil indicating head gasket issues.

There's no fixed mileage limit, it depends on maintenance. The parts worth budgeting for proactively are: Timing chain, upper guide rail, and tensioner (100,000 km), Valve stem seals (120,000 km), Valve cover gasket (80,000 km), PCV / crankcase breather system (100,000 km). Engines that clear these checkpoints with documented maintenance commonly continue well beyond typical ownership periods.

Takata airbag inflator may rupture and deploy with excessive force, posing injury or fatality risk to occupants Remedy: Replacement of passenger-side frontal airbag inflator module by BMW dealer at no cost to owner

Estimated ownership cost is €1,500-4,500 over 3 years depending on timing chain and valve seal status at purchase, based on known issues and typical service needs.

Owners report real-world fuel consumption of around 8.8 L/100km, compared to the official figure of 6.6 L/100km.

Community-reported real-world usage suggests changing oil every 10,000 km using BMW Longlife-01 5W-30 fully synthetic (e.g. Castrol Edge 5W-30 LL or Shell Helix Ultra 5W-30), often more conservative than the official service schedule.

The N46 is also found in: BMW 316i E90, BMW 318i E90/E91/E92, BMW 120i E81/E87, BMW 116i E87, BMW 118i E87, BMW Z4 2.0i E85.

Budget buy, expensive surprises lurk inside The biggest recurring complaint is Timing Chain Stretch & Guide Failure. Cautiously negative, owners acknowledge the engine's smooth character but frequently warn about timing chain costs and valve seal issues, with multiple forum threads citing repair bills of 2,500-3,500 euros as a routine ownership reality