BMW N54/N55 engine: faults and reliability

• N54B30 302 hp (2006-2010)

  2006–2010 · 302 hp · N54B30

  With caution

  It is the engine with the most documented faults in the family: high-pressure pump, injectors and wastegates; check which parts have already been replaced.^[1][3][5]

• N54 322 hp (2008-2013)

  2008–2013 · 322 hp · N54B30

  With caution

  It is the engine with the most documented faults in the family: high-pressure pump, injectors and wastegates; check which parts have already been replaced.^[1][3][5]

• N54 335 hp (2011-2016)

  2011–2016 · 335 hp · N54B30

  With caution

  It is the engine with the most documented faults in the family: high-pressure pump, injectors and wastegates; check which parts have already been replaced.^[1][3][5]

• N55B30M0 302 hp (2009-2018)

  2009–2018 · 302 hp · N55B30M0

  With caution

  Simpler than the N54 (one turbo and solenoid injectors), but it keeps the oil leaks from the filter housing and the electric water pump; check both.^[2][4][6]

• N55B30 315 hp (2011-2018)

  2011–2018 · 315 hp · N55B30

  With caution

  Simpler than the N54 (one turbo and solenoid injectors), but it keeps the oil leaks from the filter housing and the electric water pump; check both.^[2][4][6]

• N55B30O0 322 hp (2014-2016)

  2014–2016 · 322 hp · N55B30O0

  With caution

  Simpler than the N54 (one turbo and solenoid injectors), but it keeps the oil leaks from the filter housing and the electric water pump; check both.^[2][4][6]

• N55HP 335 hp (2013-2015)

  2013–2015 · 335 hp · N55HP

  With caution

  Simpler than the N54 (one turbo and solenoid injectors), but it keeps the oil leaks from the filter housing and the electric water pump; check both.^[2][4][6]

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. 1High severityFrequency: CommonFuelHigh-pressure fuel pump (HPFP) failureThe N54's high-pressure pump is one of its best-documented failures: most units will have had it replaced at some point. It warns of itself with long cranking and loss of power; the 2010 campaign was US-only.
2. 2Medium severityFrequency: CommonInjectionN54 piezoelectric injector failureThe N54's piezoelectric injectors can clog or leak and cause intermittent misfires. The N55 has solenoid injectors, so it does not share this weak point.
3. 3Medium severityFrequency: CommonTurboTurbo wastegate noise and failureOn the N54 the wastegate rods work loose and produce a metallic rattle; over time they reduce boost pressure. On the N55 it is the electric actuator that fails.
4. 4Medium severityFrequency: CommonCoolingElectric water pump and thermostat failureThe electric water pump on the N54 and N55 fails without warning, at around 100,000-150,000 km, and is usually replaced together with the thermostat. If not dealt with, the engine overheats.
5. 5Medium severityFrequency: CommonLubricationOil leak from the oil filter housing gasketThe oil filter housing gasket on the N54 and N55 leaks oil as it ages; the oil can drip onto the auxiliary drive belt, and there are also leaks from the valve cover.
6. 6Medium severityFrequency: CommonIgnitionOil in the spark plug wells from the rocker cover gasketOn the N54 and N55 the rocker cover gasket hardens with age and lets oil seep into the spark plug wells. Guides treat it as a known fault: it smells of burnt oil and can damage spark plugs and coils.

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

Manufacturer

BMW

Family

N54/N55

Fuel

Petrol

Displacement

2,979 cm³

Cylinders

6

Fuel system

Turbo

Injection

Direct injection

Timing

Chain

Power

302–335 hp

Production

2006–2019

Makes

BMW

Technical data^[1][2]

1. 2006–2010

   N54B30 302 hp (2006-2010)

   First version of the 3.0 inline-six with two small turbos and piezoelectric direct injection; 302 hp according to the Wikipedia entry.^[1]

2. 2008–2013

   N54 322 hp (2008-2013)

   322 hp output, produced between 2008 and 2013 according to Wikipedia (the exact code of this variant has not been verified).^[1]

3. 2009–2018

   N55B30M0 302 hp (2009-2018)

   Replaces the N54's two turbos with a single twin-scroll unit, and adds Valvetronic and solenoid injectors instead of piezoelectric ones; 302 hp.^[2]

4. 2011–2016

   N54 335 hp (2011-2016)

   335 hp output, produced between 2011 and 2016 according to Wikipedia; mainly associated with the 1M Coupé and special editions.^[1]

5. 2011–2018

   N55B30 315 hp (2011-2018)

   315 hp variant of the same N55 family, with the same technical solutions.^[2]

6. 2013–2015

   N55HP 335 hp (2013-2015)

   335 hp variant (N55HP) produced between 2013 and 2015 according to Wikipedia.^[2]

7. 2014–2016

   N55B30O0 322 hp (2014-2016)

   322 hp variant introduced in 2014 according to Wikipedia.^[2]