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BMW B48 / B38 vs BMW N43/N46: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the BMW N43/N46: 24/100 (low risk) versus 59/100 (high 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 N43/N46 has 1 documented serious fault, the main one being «Wear and breakage of the timing chain guides».

Risk index

BMW B48 / B38

24

Low risk · 1 serious fault

Lower risk

Risk index

BMW N43/N46

59

High risk · 1 serious fault

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

13 sourcesHow 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 N43/N46 reliable?

The BMW N43 and N46 (2004-2012) are naturally aspirated four-cylinder engines fitted to the 1 Series E87, 3 Series E90, X1 E84 and Z4 E85/E86, among others. They have a reputation for being solid if properly maintained, but share well-known wear of the timing chain guides and tensioner, of the Valvetronic and of the VANOS valves; the direct-injection N43 adds documented failures of the injectors, ignition coils and the NOx sensor.[4][5][6][7]

See the 4 of the BMW N43/N46 faults

Side-by-side comparison

Comparison of BMW B48 / B38 and BMW N43/N46
BMW B48 / B38BMW N43/N46
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement1,998 cm³—
TimingChainChain
Power136–312 hp121–170 hp
Productionsince 2014[1][8][9]2004–2012[4][5][10][11]
Reliability
Risk index (what is it?)24Low risk59High risk
Documented faults44
Of high or critical severity11
Worst severityHigh severityCritical severity
Main faults
  1. Medium severity: Deterioration of hoses and seals in the cooling circuit, with coolant loss
  2. Medium severity: Oil leaks or seepage from seals and covers, near the turbo and the VANOS
  3. High severity: Timing chain on the early units (2014-2018), redesigned in the B48TU
  1. Critical severity: Wear and breakage of the timing chain guides
  2. Medium severity: Injector, ignition coil and NOx sensor failures (N43)
  3. Medium severity: Wear of the Valvetronic and the VANOS solenoid valves
Most expensive documented repairNo reliable dataNo 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][12]
  • B48 2.0 up to 302-312 hp, high performance (MINI John Cooper Works, BMW X1 M35i)[2]
None
With cautionVersions to be cautious aboutNone
  • N46B20 127-148 hp, indirect injection (2004-2007)[6][7]
  • N46NB20 150-170 hp, revised ECU (2006-2012)[6][7][13]
  • N43B16 121 hp, 1.6 litres (2007-2011)[4][6]
  • N43B20 121-168 hp, 2.0 litres (2007-2013)[4][6]
AvoidVersions to avoidNoneNone

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 N43/N46

Other comparisons

With the BMW B48 / B38

With the BMW N43/N46

Compare other engines

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Sources

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

  1. BMW B48Wikipedia (inglés) · Other source · consulted 27 September 2026
  2. Motor BMW B48: defectos, mantenimiento y guía de compraRecambios y Accesorios BMW (blog) · Technical documentation · consulted 27 September 2026 · in Spanish
  3. BMW Reliability Has Changed, But the Internet Hasn't Caught UpBMWBLOG · Other source · published January 2026 · consulted 27 September 2026
  4. BMW N43Wikipedia (inglés) · Other source · consulted 27 September 2026
  5. BMW N46Wikipedia (inglés) · Other source · consulted 27 September 2026
  6. BMW N43: Bei diesem Benziner ist Ärger vorprogrammiertGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  7. BMW N46: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  8. BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
  9. BMW B48Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  10. BMW N43Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  11. BMW N46Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  12. 5 BMWs That Prove the B48 Four-Cylinder Engine Is Better Than You ThinkBMWBLOG · Other source · published April 2026 · consulted 27 September 2026
  13. BMW X1 E84 – Bekannte Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · published 9 May 2023 · consulted 27 September 2026 · in German