BMW S65B40 engine code explained
S65B40 is the full code for the 4.0-litre naturally aspirated V8 in the E90, E92 and E93 M3 of 2007 to 2013, essentially the S85 V10 minus two cylinders. It revs to 8,400 rpm, makes 414 bhp, and has a well-documented rod-bearing wear pattern that every buyer prices in. The 4.4-litre S65B44 in the M3 GTS and CRT is the only variant.
Quick answer
The S65B40 is the 4.0-litre V8 naturally aspirated M engine petrol of the BMW S65 family, built 2007-2013. Bimmer.AI scores the family 7 / 10: a strong used buy with a short list of known preventatives. The tables below give every output tier and sticker letter BMW used on this stem and which cars got them; the failure table is the same one that powers the S65 family guide.
How to read S65B40
| Part of the code | Meaning |
|---|---|
| S | BMW M GmbH (M Division) engine |
| 65 | engine family number within the S-series |
| B | petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4) |
| 40 | displacement in tenths of a litre: 4.0 litres |
| K / U / M / O / T / S + digit | output tier and revision, appended in BMW's internal naming (for example S65B40O1) |
| A / B / C / D | parts-catalogue engine version printed on the engine cover sticker (for example S65B40A) |
S65B40 output tiers and which cars have them
| Code | Output | Cars | Notes |
|---|---|---|---|
| S65B40 | 414 bhp | M3 (E90 saloon 2008-2011, E92 coupe 2007-2013, E93 convertible 2008-2013) | The M3 engine |
| S65B44 | 444 bhp | M3 GTS (E92 2010, 135 cars), M3 CRT (E90 2011, 67 cars) | 4.4-litre limited edition |
S65B40 sticker letters: S65B40A
No buyer-relevant split. The S65 conversation is rod bearings (£1,500 to £2,500 at 60,000 to 80,000 miles, with an oil analysis first on any unknown car), throttle actuators (a pair fail past 80,000 miles, £800 to £1,500 or specialist rebuilds), and VANOS oil-pressure-line hoses. A car with all three done is a future classic; one with none is a project.
| Sticker code | What it denotes |
|---|---|
| S65B40A | Standard parts-catalogue version for all M3 applications. |
Known problems on every S65B40
Failure data is held once, per engine family, so this table is identical to the BMW S65 guide. Cost ranges are indicative UK figures.
| Failure mode | Severity | Frequency | Typical onset | UK repair range |
|---|---|---|---|---|
| Rod bearing wear | Catastrophic | Very common | 50 to 100k mi | £1,500 to £2,500 |
| Throttle actuator failure (8 individual units) | Moderate | Very common | 40 to 130k mi | £250 to £1,500 |
| VANOS solenoid weep | Mild | Common | 60 to 130k mi | £200 to £400 |
| Oil pump anti-rotation nut | Catastrophic | Uncommon | 60 to 150k mi | £200 to £500 |
| Coolant pump and thermostat | Moderate | Common | 60 to 130k mi | £400 to £700 |
Long-term verdict
Future-classic naturally aspirated V8: 8200 rpm redline, individual throttle bodies, 414 bhp from 4.0 litres. Mandatory preventative is rod-bearing replacement at 60,000 to 80,000 miles (£1,500 to £2,500). Throttle actuators (8 individual units) are wear items. With both addressed and disciplined oil intervals, 200,000+ miles is realistic.
Check a specific S65B40 listing
Paste any BMW S65 listing, VIN or registration. Bimmer.AI identifies the exact engine and returns the buyer report in 30 seconds.
Run a Bimmer.AI buyer report →Bimmer.AI is designed to help you identify BMW-specific buyer risks before you travel, negotiate, or pay for an inspection. It does not replace a physical inspection by a qualified mechanic, a legal vehicle-history check (e.g. HPI Check), or independent verification of finance, stolen, or write-off status. Repair-cost ranges are indicative UK figures that vary by region, specialist, parts supply, and labour rates.
Frequently asked questions
S65B40 rod bearings: at what mileage?
Specialists recommend replacement between 60,000 and 80,000 miles, or sooner on tracked cars: £1,500 to £2,500 at an independent M specialist, often with an oil analysis first to look for lead and copper. BMW never issued a recall. Documented bearings are the single biggest value item on an E9x M3.
What else fails on the S65B40?
The two throttle-body actuators (one per bank) fail past 80,000 miles and put the car into limp mode; £800 to £1,500 for new units or less via specialist rebuilds. The VANOS high-pressure oil lines can weep, and the ionic-current knock system misreads with the wrong spark plugs. Otherwise it is a durable engine that rewards 5,000-mile oil changes.
Which BMWs have the S65B40 engine?
The S65B40 went into the following cars, by output tier. S65B40 (414 bhp): M3 (E90 saloon 2008-2011, E92 coupe 2007-2013, E93 convertible 2008-2013); S65B44 (444 bhp): M3 GTS (E92 2010, 135 cars), M3 CRT (E90 2011, 67 cars). The two-letter family badge is S65; any listing that quotes the family code is talking about one of these.
Is the BMW S65B40 reliable?
Bimmer.AI scores the S65 family 7 out of 10, which makes the S65B40 a strong used buy with a short list of known preventatives. Future-classic naturally aspirated V8: 8200 rpm redline, individual throttle bodies, 414 bhp from 4.0 litres. Mandatory preventative is rod-bearing replacement at 60,000 to 80,000 miles (£1,500 to £2,500). Throttle actuators (8 individual units) are wear items. With both addressed and disciplined oil intervals, 200,000+ miles is realistic.
What does S65B40 mean?
S is the BMW M GmbH (M Division) engine, 65 is the family number, B means petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4), and 40 is the displacement in tenths of a litre (4.0 litres). BMW appends an output tier and revision (K, U, M, O, T or S plus a digit) in its own naming, and the parts catalogue adds a version letter (A, B, C) that is what you see on the engine cover.