BMW B48 / B38 vs BMW N54/N55: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the BMW N54/N55: 24/100 (low risk) versus 48/100 (moderate risk). The BMW B48 / B38 has 1 documented serious fault, the main one being «Timing chain on the early units (2014-2018), redesigned in the B48TU»; the BMW N54/N55 has 1 documented serious fault, the main one being «High-pressure fuel pump (HPFP) failure».

Risk index

BMW B48 / B38

Low risk · 1 serious fault

Lower risk

Risk index

BMW N54/N55

Moderate risk · 1 serious fault

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 5 October 202612 sources How we work

Is the BMW B48 / B38 reliable?

The BMW B48 (2.0 turbo, from 2014) and its three-cylinder sibling, the B38 (1.5), have a reputation as reliable engines within BMW's modern range: there is no serious, widespread fault on record, unlike the timing chain on the N47 diesel or the EGR fire risk on the B47. Keep an eye on the cooling circuit, the oil seals near the turbo and the VANOS, and the carbon build-up typical of direct injection; BMW revised the timing chain in 2018 (B48TU update).^[1][2][3]

See the 4 of the BMW B48 / B38 faults

Is the BMW N54/N55 reliable?

The N54 (2006-2016) is a 3.0-litre twin-turbo straight-six with many documented faults: high-pressure pump, injectors and wastegates. The N55 (2009-2019) uses a single turbo and is considered simpler, although it shares oil leaks from the filter housing and the electric water pump.^[4][5][6][7]

See the 6 of the BMW N54/N55 faults

Side-by-side comparison

Comparison of BMW B48 / B38 and BMW N54/N55
Item	BMW B48 / B38	BMW N54/N55
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,998 cm³	2,979 cm³
Timing	Chain	Chain
Power	136–312 hp	302–335 hp
Production	since 2014^[1][8][9]	2006–2019^[4][5]
Reliability
Risk index (what is it?)	24Low risk	48Moderate risk
Documented faults	4	6
Of high or critical severity	1	1
Worst severity	High severity	High severity
Main faults	Medium severity: Deterioration of hoses and seals in the cooling circuit, with coolant loss Medium severity: Oil leaks or seepage from seals and covers, near the turbo and the VANOS High severity: Timing chain on the early units (2014-2018), redesigned in the B48TU	High severity: High-pressure fuel pump (HPFP) failure Medium severity: N54 piezoelectric injector failure Medium severity: Turbo wastegate noise and failure
Most expensive documented repair	No reliable data	No reliable data
Which versions to buy
BuyRecommended versions	B38 1.5 136 hp (MINI Cooper, 118i)^[2] B48 2.0 178-197 hp (120i, 220i, 320i, 520i, X1/X2/X3 20i, MINI Cooper S)^[2] B48 2.0 252-258 hp (330i, 530i, X3/X4 xDrive30i)^[2][10] B48 2.0 up to 302-312 hp, high performance (MINI John Cooper Works, BMW X1 M35i)^[2]	None
With cautionVersions to be cautious about	None	N54B30 302 hp (2006-2010)^[4][6][11] N54 322 hp (2008-2013)^[4][6][11] N54 335 hp (2011-2016)^[4][6][11] N55B30M0 302 hp (2009-2018)^[5][7][12] N55B30 315 hp (2011-2018)^[5][7][12] N55B30O0 322 hp (2014-2016)^[5][7][12] N55HP 335 hp (2013-2015)^[5][7][12]
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

BMW B48 / B38

See the 17 models with the BMW B48 / B38

BMW N54/N55

See the 13 models with the BMW N54/N55

Other comparisons

With the BMW B48 / B38

With the BMW N54/N55

Compare other engines

First engine

Second engine

That is the comparison you are viewing: change one of the two engines.

Sources

Every fact on this page links to its source. If you find an error, let us know.

BMW B48Wikipedia (inglés) · Other source · consulted 27 September 2026
Motor BMW B48: defectos, mantenimiento y guía de compraRecambios y Accesorios BMW (blog) · Technical documentation · consulted 27 September 2026 · in Spanish
BMW Reliability Has Changed, But the Internet Hasn't Caught UpBMWBLOG · Other source · published January 2026 · consulted 27 September 2026
BMW N54Wikipedia · Other source · consulted 5 October 2026
BMW N55Wikipedia · Other source · consulted 5 October 2026
Todo lo que necesitas saber sobre el motor BMW N54High Performance Academy · Technical documentation · consulted 5 October 2026 · in Spanish
BMW N55 Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · published 23 February 2025 · consulted 5 October 2026 · in German
BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
BMW B48Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
5 BMWs That Prove the B48 Four-Cylinder Engine Is Better Than You ThinkBMWBLOG · Other source · published April 2026 · consulted 27 September 2026
The Definitive Guide to the BMW N54 EngineFCP Euro · Technical documentation · consulted 5 October 2026
BMW N55 Common ProblemsBMW Tuning · Technical documentation · consulted 5 October 2026