BMW X6 40i Engine ReplacementCompare Prices & Get Quotes

A BMW X6 40i engine replacement typically costs £2,500-£5,000 supply-only for a reconditioned B58, or £3,500-£5,800 for a rebuilt unit. Fitted by a specialist, expect £4,500-£8,000 total.

• B58B30C (2019-2020) reconditioned: £2,500-£4,200 supply-only
• B58B30M1 (2020-2023) reconditioned: £2,800-£4,500 supply-only
• B58B30P (2023+) reconditioned: £3,200-£5,000 supply-only
• Professional fitting adds £1,500-£2,500 depending on your location and workshop

Common warning signs of B58 issues include low coolant warnings, reduced power (drivetrain malfunction), and unusual noises from the engine bay.

• Low coolant light may indicate expansion tank cracks or system leaks
• Drivetrain malfunction with loss of boost often points to charge pipe failure
• Whining noises may indicate water pump or PCV system issues
• Check engine lights require immediate diagnosis - the B58 is robust but not invincible

For a G06 X6 40i worth £35,000-£60,000, engine replacement (£3,500-£5,800 supply-only) typically represents 10-20% of the vehicle's value - making it a financially viable option for most owners.

• Compare replacement cost against vehicle value - replacement is viable up to roughly 60-70% of the car's value
• Given the high vehicle value, replacement is usually justified if the body and interior are in excellent condition
• Low-mileage, well-serviced, or cherished 40i examples justify the investment
• Always factor the 12-month warranty into your decision

The B58 is widely considered BMW's most reliable modern petrol engine. With proper maintenance, 150,000-200,000 miles is achievable before major work.

• Regular oil changes (every 8,000-10,000 miles) are critical for longevity
• Coolant system components (expansion tank, water pump) are wear items - replace every 60,000-80,000 miles as preventative maintenance
• The B58's closed-deck design and robust internals make it exceptionally durable
• Charge pipe failure is the most common boost-related issue - upgraded aluminium pipes are a permanent fix

The B58B30C (2019-2020) is the initial G06 X6 40i engine producing 340hp. The B58B30M1 (2020-2023) is a production refinement with the same power output. The B58B30P (2023+) introduced 48V mild-hybrid assistance, increasing power to 381hp and adding 12hp electric boost.

• B58B30C and B58B30M1: 340hp, no mild-hybrid
• B58B30P: 381hp with 48V MHEV, improved fuel economy and smoother stop-start
• All are 3.0L (2998cc) straight-six turbo petrol engines
• Engine bays are similar - replacement is direct bolt-in for the correct generation

Swapping a 40i's B58 petrol for a diesel (xDrive30d/40d B57) is technically complex and rarely cost-effective. The engines have different mounts, wiring looms, ECUs, cooling systems, and fuel systems.

• B58 is a 3.0L petrol; B57 is a 3.0L diesel - fuel system, ECU and exhaust are completely different
• Transmission may also differ - petrol and diesel X6s use different gearbox calibrations
• Insurance must be notified of any non-standard engine swap
• Stick to like-for-like code-matching for warranty coverage and straightforward installation