BMW M135i F20 — Reliability

F20 Hatchback Compact 2012–2019 2 engines

Reliability Summary

Best engine B58 — 93/100 BEST
Worst engine N55 — 76/100 ACCEPTABLE
Average reliability 84/100

Engine Comparison

Engine Reliability Score Verdict Known Issues
B58
3.0L Turbo I6 		93/100 BEST Coolant expansion tank / line failure — early units +2
N55
3.0L Turbo I6 		76/100 ACCEPTABLE Electric water pump failure +4

Engines in this model

BEST 93

B58

3.0L Turbo I6

Possibly BMWs best engine ever. Forged internals, insane tuning (600hp+). 300k+ km.

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ACCEPTABLE 76

N55

3.0L Turbo I6

Fixed N54. Known issues cheap + documented. 200k+ km proven. Good tuning base.

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Known Issues Across All Engines

Issue Engine Severity Onset
Coolant expansion tank / line failure — early units B58 moderate 60,000 km – 120,000 km
Plastic charge pipe crack B58 minor 60,000 km – 150,000 km
Valve cover gasket oil leak B58 minor 80,000 km – 160,000 km
Electric water pump failure N55 high 60,000 km – 120,000 km
Valve cover gasket oil leak N55 moderate 60,000 km – 130,000 km
Oil filter housing gasket (OFHG) leak N55 moderate 60,000 km – 130,000 km
Plastic charge pipe crack N55 moderate 60,000 km – 150,000 km
Coolant pipe / banjo bolt seals N55 minor 80,000 km – 150,000 km

FAQ

Is the BMW M135i reliable?

The BMW M135i has 2 engine options with reliability scores ranging from 76/100 (ACCEPTABLE) to 93/100 (BEST). Average reliability: 84/100.

Which BMW M135i engine is most reliable?

The B58 is the most reliable engine in the BMW M135i, scoring 93/100 (BEST).

What problems does the BMW M135i have?

Across all engine variants, the BMW M135i has 8 known issues. The most common are related to Coolant expansion tank / line failure — early units, Plastic charge pipe crack, Valve cover gasket oil leak.