BMW i Series Electric Motor & Hybrid SpecialistCompare Quotes

A replacement BMW i3 REx engine typically costs £1,850-£2,950 supply-only for a rebuilt unit, or £700-£1,400 for specialist generator bearing replacement.

• Dealer replacement: £3,500-£5,500 supply & fit (often with long lead times)
• Specialist rebuilt B38A15R: £1,850-£2,950 supply only
• Generator bearing replacement (intermediate fix): £700-£1,200 at a specialist
• Used units from verified donors: £1,200-£2,500 depending on mileage
• Prices exclude fitting - add £450-£850 for certified installation

Carbon buildup from infrequent generator use is the #1 killer of i3 REx engines, followed by generator bearing wear at 40,000-80,000 miles.

• Carbon buildup restricts intake valves, reducing generator output
• Symptoms: rough running when REx activates, loss of charging range
• Carbon cleaning (walnut blasting) costs £250-£450 at a specialist
• Generator bearing failure causes rattling noise - replace bearings promptly
• Regular REx exercise prevents carbon - run it monthly for 20+ minutes

The B38A15T0 is generally robust, but timing chain wear (60k-80k miles) and HPFP failure are documented weak points owners should budget for.

• Timing chain stretch causes cold-start rattling - replace preventatively
• High-pressure fuel pump (HPFP) failure leads to rough idle and stalling
• HPFP replacement at specialist: £700-£1,400
• Timing chain replacement: £1,200-£2,200 at independent specialist
• B38 engine won International Engine of the Year 2015

Independent BMW i specialists typically charge 25-50% less than main dealers while delivering equal or better expertise on electrified powertrains.

• Dealer rates are 20-30% higher due to overhead and OEM parts markup
• Independent specialists see i3/i8 daily - faster diagnostics, fewer trial repairs
• Both preserve manufacturer warranty when using correct parts and procedures
• Specialists offer flexible parts options (OEM or quality aftermarket)
• Always verify high-voltage certification for drive unit work

New OEM REx units are increasingly difficult to source and carry dealer pricing of £3,500-£5,500 - most owners now choose rebuilt or reconditioned units.

• BMW has discontinued new REx engine production for the i3
• Remaining dealer stock commands premium pricing with long lead times
• Rebuilt units use upgraded components (bearings, injectors, seals)
• Reconditioned engines include 12-month warranty as standard
• Used donor engines from breakers available from £1,200-£2,500

Walnut blasting removes carbon deposits from intake valves - a £250-£450 service that restores generator performance and can prevent full engine replacement.

• Carbon buildup is inevitable on direct-injection REx engines from infrequent use
• Symptoms: reduced range, rough running, check engine lights
• Walnut blasting is safe - crushed shells remove carbon without damaging metal
• Benefits: restored power, smoother idle, better fuel efficiency
• Recommended every 30,000-60,000 miles depending on driving patterns

Electric drive units typically last 100,000-150,000 miles, but bearing wear can appear from 50,000 miles on early EM100 units.

• EM100 series (2013-2016): bearing wear possible from 50k miles
• EM100-2 (2016-2018): revised bearings, longer lifespan
• EM200/EM300 (2018+): reinforced rotors, improved durability

Used REx engines are viable from £1,200-£2,500, but always verify generator bearing condition, carbon history, and mileage before purchase.

• Request video of engine running before buying
• Verify bearing health - rattling indicates imminent failure
• Low-mileage units (under 40k miles) preferred
• Check service history for regular REx exercise
• Most suppliers offer 30-90 day warranty on used units

Every engine supplied through EngineMarket includes a minimum 12-month unlimited mileage warranty - reconditioned and rebuilt units typically offer longer coverage.

• Rebuilt engines: 12-24 month warranty with upgraded components
• Reconditioned units: 12 months parts and labour minimum
• Used engines: 30-90 days depending on supplier
• Supply & fit packages include labour warranty
• Always confirm exact terms with your chosen supplier

With i3 REx values at £6,000-£10,000, a £1,850-£2,950 rebuilt engine makes financial sense - carbon cleaning at £250-£450 is even better value.

• 2014-2016 i3 REx values: £5,000-£8,000 depending on condition
• Rebuilt engine cost: ~25-35% of vehicle value - typically worth doing
• Preventative carbon cleaning (£250-£450) extends engine life significantly
• Compare against dealer replacement quotes (£3,500-£5,500)
• Well-maintained i3 REx remains in strong used demand