N42 and N45 1.6, 1.8 and 2.0 engine: faults and reliability

• N42B18, 1.8 litres with Valvetronic (115 hp; 2001-2004)

  2001–2004 · 115 hp · N42B18

  With caution

  Gebrauchtwagenberater considers it a risky purchase: it recommends it only with a complete, documented service history and with the chain, tensioner and guides already replaced. Set aside money for repairs.^[1][3]

• N42B20, 2.0 litres with Valvetronic (143 hp; 2001-2004)

  2001–2004 · 143 hp · N42B20

  With caution

  It shares the weak points of the family with the 1.8: chain and tensioner, Valvetronic and oil leaks. Buy only with an invoice for the chain and tensioner and with no idle faults.^[1][3][8]

• N45B16 and N45NB16, 1.6 litres without Valvetronic (116 hp; 2003-2011)

  2003–2011 · 116 hp · N45B16, N45NB16

  With caution

  Gebrauchtwagenberater rates it 'bedingt empfehlenswert' (recommendable with conditions): a complete, verifiable history, chain with tensioner and guides already replaced, and reasonable consumption of around 8 to 9 l/100 km according to that source.^[2]

Buy: No known serious faults, or they have already been corrected, in this version. With caution: Worth buying if something specific is verified: history, a replaced part or a completed campaign. Avoid: High risk of a serious fault that is hard to check for or prevent.

1. 1Critical severityFrequency: CommonTimingTiming chain stretch and tensioner wearThe N42 and N45 can stretch the timing chain, usually because of a faulty tensioner, and the warning sign is a rattle when cold. If the chain jumps teeth, the engine can suffer serious damage. On the N42, BMW later released a revised, longer tensioner.
2. 2Medium severityFrequency: CommonLubricationOil leaks from the rocker cover and oil consumptionWith age, the N42 and N45 can lose or burn oil. Gebrauchtwagenberater points to the rocker cover gasket and valve stem seals on both and, on the N42, also to the crankcase breather and the vacuum pump.
3. 3Medium severityFrequency: OccasionalIntakeEccentric shaft sensor and Valvetronic motor faults (N42)On the N42, the eccentric shaft sensor and the Valvetronic motor can degrade and cause rough idle and erratic behaviour. The sources point to a worn eccentric shaft or a faulty actuator motor. The N45 has no Valvetronic and is not affected.
4. 4Medium severityFrequency: OccasionalLubricationBlocked crankcase ventilation valve (CCV)The N42's crankcase ventilation (CCV) can become blocked, especially with short trips in cold weather, and cause rough idle, higher oil consumption, hard cold starts and lack of low-rev power. Replacing it means removing the intake manifold.
5. 5Medium severityFrequency: OccasionalTimingVANOS solenoid valve failureThe VANOS solenoid valves can fail over time on the N42 and N45, according to Gebrauchtwagenberater, with unstable low-rev running, loss of power and sometimes difficult starting. CarWiki also cites the N45's VANOS among the weak points.

Severity colours: low, medium, high, critical. How we rate them

Manufacturer

BMW

Family

N42 y N45 (sucesores del M43; precursores del N46)

Fuel

Petrol

Displacement

—

Cylinders

4

Fuel system

Naturally aspirated

Injection

Indirect injection

Timing

Chain

Power

115–143 hp

Peak torque

200 Nm

Production

2001–2011

Makes

BMW

Technical data^{[1][2][4][5][6][7]}

1. 2001–2004

   N42B18, 1.8 litres with Valvetronic (115 hp; 2001-2004)

   BMW's first engine with Valvetronic: 1.8 litres, 85 kW (115 hp) and 175 N·m, 16 valves and double VANOS. It powered the E46 316i and 316ti Compact from June 2001 until 2004 and replaced the M43.^[4][5][13]

2. 2001–2004

   N42B20, 2.0 litres with Valvetronic (143 hp; 2001-2004)

   The 2.0-litre version of the N42: 105 kW (143 hp) and 200 N·m, with Valvetronic, double VANOS and, according to the German Wikipedia, a two-stage DISA intake manifold. It powered the E46 318i, 318Ci and 318ti Compact between 2001 and 2004.^[4][5][13]

3. 2003–2011

   N45B16 and N45NB16, 1.6 litres without Valvetronic (116 hp; 2003-2011)

   Four-cylinder 1.6-litre engine, 85 kW (116 hp) and 150 N·m, with double VANOS but without Valvetronic (this is mainly what distinguishes it from the N42) and without balance shafts. The N45N revision, from 2007, introduced a new ECU and kept the power output, according to the German Wikipedia.^[6][7][14]

• Timing chain kit

  • Buy part at Autodoc (affiliate link, opens in a new tab)

• Oil filter

  • Buy part at Autodoc (affiliate link, opens in a new tab)

• Air filter

  • Buy part at Autodoc (affiliate link, opens in a new tab)

• Spark plugs

  • Buy part at Autodoc (affiliate link, opens in a new tab)