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BMW B58 vs BMW N43/N46: which engine is more reliable?

According to our risk index, the BMW B58 carries less risk than the BMW N43/N46: 38/100 (moderate risk) versus 59/100 (high risk). The BMW B58 has 1 documented serious fault, the main one being «Failure of the oil pump with a plastic rotor housing»; the BMW N43/N46 has 1 documented serious fault, the main one being «Wear and breakage of the timing chain guides».

Risk index

BMW B58

38

Moderate 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

14 sourcesHow we work

Is the BMW B58 reliable?

The B58 (3.0 turbo straight-six, since 2015) is considered robust and less troublesome than the N54/N55 it replaced, and the sources do not document widespread internal failures. The known faults are on the periphery: the plastic oil filter housing, crankcase ventilation, gaskets and coolant. On units built before 2021 there are also US reports of an oil pump with a plastic housing.[1][2][3][4]

See the 6 of the BMW B58 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.[5][6][7][8]

See the 4 of the BMW N43/N46 faults

Side-by-side comparison

Comparison of BMW B58 and BMW N43/N46
BMW B58BMW N43/N46
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement2,998 cm³—
TimingChainChain
Power290–441 hp121–170 hp
Productionsince 2015[9][10]2004–2012[5][6][11][12]
Reliability
Risk index (what is it?)38Moderate risk59High risk
Documented faults64
Of high or critical severity11
Worst severityHigh severityCritical severity
Main faults
  1. High severity: Failure of the oil pump with a plastic rotor housing
  2. Medium severity: Oil and coolant leak from the plastic oil filter housing
  3. Medium severity: Failure of the crankcase ventilation PCV valve (integrated in the valve cover)
  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
  • B58TU2 381 hp (B58B30M2, since 2022)[2][3]
None
With cautionVersions to be cautious about
  • B58 326 hp (B58B30M0, 2015-2019)[2][3][13]
  • B58 340-360 hp (B58B30M0, 2016-2019)[2][3][13]
  • B58TU 333-340 hp (B58B30M1, since 2018)[2][3]
  • B58TU 374 hp (B58B30O1, M340i, M440i and M240i, since 2019)[3]
  • N46B20 127-148 hp, indirect injection (2004-2007)[7][8]
  • N46NB20 150-170 hp, revised ECU (2006-2012)[7][8][14]
  • N43B16 121 hp, 1.6 litres (2007-2011)[5][7]
  • N43B20 121-168 hp, 2.0 litres (2007-2013)[5][7]
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 B58

See the 15 models with the BMW B58

BMW N43/N46

Other comparisons

With the BMW B58

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. The 5 Most Common BMW B58 Engine ProblemsBMW Tuning · Technical documentation · published 7 February 2020 · consulted 9 October 2026
  2. BMW B58 EngineFCP Euro · Technical documentation · consulted 9 October 2026
  3. The Popular BMW B58 Inline-Six Engine Has One Big Achilles HeelThe Autopian · Motoring press · published 14 June 2024 · consulted 9 October 2026
  4. ¿En qué se diferencian los motores B58 y S58 de BMW?Diariomotor · Motoring press · published 27 April 2024 · consulted 9 October 2026 · in Spanish
  5. BMW N43Wikipedia (inglés) · Other source · consulted 27 September 2026
  6. BMW N46Wikipedia (inglés) · Other source · consulted 27 September 2026
  7. BMW N43: Bei diesem Benziner ist Ärger vorprogrammiertGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  8. BMW N46: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  9. BMW B58Wikipedia (inglés) · Other source · consulted 9 October 2026
  10. BMW B58Wikipedia (alemán) · Other source · consulted 9 October 2026 · in German
  11. BMW N43Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  12. BMW N46Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  13. How A Plastic Part On BMW's B58 Engine Can Turn An Oil Change Into A $3,000 RepairThe Autopian · Motoring press · published 28 March 2025 · consulted 9 October 2026
  14. BMW X1 E84 – Bekannte Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · published 9 May 2023 · consulted 27 September 2026 · in German