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BMW N43B20 Engine (Design, Specs, Reliability)

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From 2007 to 2011, BMW developed the 4-cylinder inline gasoline BMW N43B20 engine, it produces 122-170 hp and 185-210 nm of torque.

There are three variations of the N43 engine, which is well-known and well-liked by drivers all over the globe.

  1. N43B20K0 – reduced power variant with 185 Nm of torque at 3000 rpm and 122 horsepower at 6000 rpm. The motor was mounted on the BMW model with the 16i name.
  2. N43B20U0 – for BMW cars with the 18i name, with 143 horsepower at 6000 rpm and 190 Nm of torque at 4250 rpm.
  3. N43B20O0 – most powerful version for BMW cars with the 20i name. 170 horsepower at 6700 rpm, and 210 Nm of torque at 4250 rpm.

In this article, we’ll be discussing the design, reliability and issues of the BMW N43B20 engine.

Design of the BMW N43B20 Engine

The new BMW N43 engine has Valvetronic valve lift systems and direct fuel injection in contrast to its predecessor, the N42 engine.

The engine was built alongside other components like the N45 and N46, but at this time, it outsold them in terms of demand.

It is not always simple to combine economy and environmental friendliness with an ideally high level of torque, but that is what this engine has been built to do.

BMW N43B20

N43B20 Engine Specs

  • Production years: 2007-2011
  • Displacement: 1995 cc
  • Fuel system: direct injection
  • Power output: 122 hp @ 6000 rpm, 143 hp @ 6000 rpm, 170hp @ 6700 rpm
  • Torque output: 185 nm @ 3000 rpm, 190 nm @ 4250 rpm, 210 nm @ 4250 rpm
  • Block: aluminum R4
  • Cylinder head: aluminum 16v
  • Bore: 84 mm
  • Stroke: 90 mm
  • Compression ratio: 12.0:1
  • Hydraulic lifters: yes
  • Timing drive: chain
  • Phase regulator: double VANOS
  • Turbocharging: no
  • Recommended engine oil: 5W-30
  • Engine oil capacity: 4.25 litres
  • Fuel type: Petrol
  • Euro standards: EURO 4/5
  • Fuel consumption, L/100 km: city 8.3, highway 5.3, combined 6.4
  • Engine lifespan: ~250 000 km

Reliability & Issues of the BMW N43B20

It is important to regularly check the cooling system since it is easy to overheat. Additionally, this series’ power unit has a high fuel and oil need.

Particularly meticulous quality control is needed for oil.

Uncertified oil will start to degrade as soon as the engine is operating at a high temperature, which can eventually cause serious issues.

Therefore, it is advised to only use the oil the manufacturer has approved for N43B20. The engine will operate longer than it was designed to with proper maintenance and care.

  • Motor housing vibration. Due to the injectors’ failure, this breakdown often occurs on the N43. As a result, the latter will need to be completely replaced.
  • Engine speed fluctuations. The malfunctioned ignition coils are to blame for the failure. Replacement is necessary.
  • Vacuum pump leaks. Every 70 thousand kilometres of the distance travelled, this issue manifests. It must be changed in order to solve the issue.


N43B20 engine
BMW N43B20 engine
  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer.He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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