The BMW B58 is the 3.0L turbocharged inline-6 in the M340i, X3 M40i, X4 M40i, X5 40i, Z4 M40i, and famously the Toyota A90 Supra. Modern, robust, and capable of huge power - widely regarded as one of the best straight-6s ever built.
Excellent reliability for a modern turbo BMW. Oil pan gasket and water pump are the most common failures. Tunes are common and well-tolerated.
Oil pan gasket weeps by 60-90K. Drips onto exhaust. Standard BMW oil-leak labor.
View diagnosis →Like other modern BMWs, the electric water pump is a wear item by 80-100K. Replace with thermostat together.
View diagnosis →Develops slow seep around 60-80K. Burning-oil smell after hard driving.
View diagnosis →Stock plastic charge pipe handles 500+ hp on stock cars but tunes can crack it. Aftermarket aluminum is an inexpensive insurance.
View diagnosis →Pure DI, but the B58 has a milder buildup rate than the older N54/N55. Walnut blast at 80-100K.
View diagnosis →Recurring BMW theme. Slow oil leak from the filter housing.
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None really - the B58 is solid across all years
2019+ B58 (B58TU updated version with revised cooling and intake)
Annual maintenance $700-1,000. Major service at 100K (water pump + gaskets) $2,500-4,000. Total non-routine over 150K: $4,000-7,000.
If your BMW is throwing a check engine light, these are the codes most often associated with the problems above. Click any code for full diagnosis steps and typical repair costs.
🔬 Run a free AI diagnosis →Yes - one of the best modern BMW engines. Robust bottom end, strong cooling, and proven to handle 600+ hp on built turbo setups.
Yes - it tolerates Stage 1 and Stage 2 tunes very well. Many B58 owners run 450-550 hp daily without issue.
Easily 200,000 miles with standard maintenance. The Supra A90 has been through dyno and torture testing without bottom-end issues.
The TU (Technical Update) starting 2019 adds revised cooling, updated turbo, and minor head changes. Both are excellent.
Absolutely - the B58-powered M340i is one of the most reliable and quickest BMWs you can buy used.