BMW N62B44 engine code explained
N62B44 is the full code for the 4.4-litre version of BMW's first Valvetronic V8, fitted to the E65 745i, E60 545i, E63 645Ci and E53 X5 4.4i between 2001 and 2005. It is the engine with the valve-stem-seal reputation: the seals harden with age, the car smokes on start-up and the fix is a heads-off job that defines used pricing on every N62 car. The 4.8-litre N62B48 replaced it from 2005.
Quick answer
The N62B44 is the 4.4-litre V8 naturally aspirated petrol of the BMW N62 family, built 2001-2005. Bimmer.AI scores the family 5 / 10: buyable with evidence of the major preventative work, otherwise a negotiation. 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 N62 family guide.
How to read N62B44
| Part of the code | Meaning |
|---|---|
| N | N-series engine generation (2001 to about 2015) |
| 62 | engine family number within the N-series |
| B | petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4) |
| 44 | displacement in tenths of a litre: 4.4 litres |
| K / U / M / O / T / S + digit | output tier and revision, appended in BMW's internal naming (for example N62B44O1) |
| A / B / C / D | parts-catalogue engine version printed on the engine cover sticker (for example N62B44A) |
N62B44 output tiers and which cars have them
| Code | Output | Cars | Notes |
|---|---|---|---|
| N62B44 | 329 bhp | 745i / 745Li (E65 / E66 2001-2005), 545i (E60 / E61 2003-2005), 645Ci (E63 / E64 2003-2005), X5 4.4i (E53 2004-2006) | Single tier |
N62B44 sticker letters: N62B44A
No buyer-relevant split by letter. Every N62B44 needs the same three questions answered: have the valve stem seals been done (£2,500 to £4,000 heads-off), has the coolant transfer pipe been done (the 2001 to 2005 unit shares the valley-pipe design with the later N63), and has the Alusil bore wear been checked on a car with patchy oil history.
| Sticker code | What it denotes |
|---|---|
| N62B44A | Standard parts-catalogue version for all 4.4-litre applications. |
Known problems on every N62B44
Failure data is held once, per engine family, so this table is identical to the BMW N62 guide. Cost ranges are indicative UK figures.
| Failure mode | Severity | Frequency | Typical onset | UK repair range |
|---|---|---|---|---|
| Valve stem seal failure | Serious | Very common | 80 to 130k mi | £2,500 to £4,000 |
| Coolant transfer pipe failure (early signal for N63) | Moderate | Common | 90 to 150k mi | £1,200 to £2,000 |
| Alusil cylinder wear with poor oil maintenance | Catastrophic | Uncommon | 120 to 250k mi | £4,000 to £8,000 |
| Lifter ticking | Mild | Common | 60 to 200k mi | Free (recall) or up to £1,400 |
| Timing chain guide wear | Serious | Uncommon | 120 to 250k mi | £3,000 to £5,000 |
Long-term verdict
Big naturally aspirated V8 with big V8 character and V8 maintenance. The famous valve stem seal failure (blue smoke on cold start, rising oil consumption) is a £2,500-£4,000 heads-off job. Alusil block carries cylinder-wear risk if oil maintenance lapses. With valve stem seals addressed and disciplined 5,000-mile oil intervals, the N62 can run to 250,000+ miles. Without them, it's a slow expensive decline. Used N62 prices reflect this.
Check a specific N62B44 listing
Paste any BMW N62 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
Which BMWs have the N62B44 engine?
The E65 / E66 745i and 745Li, the E60 / E61 545i, the E63 / E64 645Ci and the E53 X5 4.4i, all between roughly 2001 and 2005 (2006 on the X5). The same architecture continued as the 4.8-litre N62B48 in the 550i, 750i, 650i and X5 4.8i, which has the same valve-stem-seal issue.
How much do N62B44 valve stem seals cost in the UK?
£2,500 to £4,000 at an independent BMW specialist, because both cylinder heads have to come off. Many specialists do the coolant transfer pipe at the same time for a few hundred pounds extra while the intake is off. A car with both jobs documented is worth a premium; a smoky one with neither is worth the price minus the whole bill.
Which BMWs have the N62B44 engine?
The N62B44 went into the following cars, by output tier. N62B44 (329 bhp): 745i / 745Li (E65 / E66 2001-2005), 545i (E60 / E61 2003-2005), 645Ci (E63 / E64 2003-2005), X5 4.4i (E53 2004-2006). The two-letter family badge is N62; any listing that quotes the family code is talking about one of these.
Is the BMW N62B44 reliable?
Bimmer.AI scores the N62 family 5 out of 10, which makes the N62B44 buyable with evidence of the major preventative work, otherwise a negotiation. Big naturally aspirated V8 with big V8 character and V8 maintenance. The famous valve stem seal failure (blue smoke on cold start, rising oil consumption) is a £2,500-£4,000 heads-off job. Alusil block carries cylinder-wear risk if oil maintenance lapses. With valve stem seals addressed and disciplined 5,000-mile oil intervals, the N62 can run to 250,000+ miles. Without them, it's a slow expensive decline. Used N62 prices reflect this.
What does N62B44 mean?
N is the N-series engine generation (2001 to about 2015), 62 is the family number, B means petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4), and 44 is the displacement in tenths of a litre (4.4 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.