BMW 4 Series Engine ReplacementCompare Prices & Save

Key points

• • N47D20C rebuilt engines start around £1,226 for 420d variants
• • B47D20A modern diesel replacements range £1,400 to £2,800 supply-only
• • Performance S55B30A M4 engines cost £5,200 to £8,800 rebuilt
• • All prices exclude fitting labour and vary by supplier warranty terms
• • Reconditioned units offer mid-tier pricing between used and remanufactured options

Key points

• • N47D20C rear-mounted chain design causes tensioner and guide wear
• • Cold-start rattling is the primary warning symptom before catastrophic failure
• • B47D20A front-chain update from 2015 onwards resolves most timing concerns
• • N20B20B petrol units share similar plastic guide degradation risks
• • Rebuilt engines include upgraded metal guides and revised tensioner kits

Key points

• • B47D20A shares mounting points with N47D20C in F32/F33 chassis
• • ECU software update essential for compatibility with newer engine management
• • xDrive models need transfer case calibration after engine swap
• • Upgrade typically costs £200-£400 more than like-for-like N47 replacement
• • Verified compatibility checks prevent costly fitment errors during installation

Key points

• • Rebuilt and reconditioned engines include 12-month unlimited mileage warranty minimum
• • Remanufactured units often feature extended 24-month coverage for peace of mind
• • Used engine warranties vary by breaker, typically 3-6 months parts-only
• • Labour coverage depends on supply-only versus supply-and-fit service selection
• • Warranty claims require proof of professional installation and service history

Key points

• • Verify donor vehicle mileage via DVLA records before purchasing any used unit
• • Request compression test results and oil pressure readings from the supplier
• • Used engines lack upgraded timing components that address known N47 weaknesses
• • Budget for potential ancillary replacement like turbos, injectors or cooling systems
• • Minimum 3-month warranty recommended to cover early failure risks

Key points

• • Reconditioned units replace visibly worn parts; remanufactured engines rebuild all critical components
• • Remanufacturing includes cylinder honing, crank polishing and pressure testing as standard
• • Reconditioned pricing typically £1,450-£3,100; remanufactured £2,800-£4,800 supply-only
• • Both options include upgraded timing components to resolve known N47 weaknesses
• • Remanufactured engines often carry 24-month warranties versus 12-month for reconditioned

Key points

• • B47D20A and B48B20A engines benefit from front-chain design and improved cooling
• • Annual oil changes using BMW Longlife-04 spec prevent premature turbo wear
• • DPF regeneration cycles require regular motorway driving to avoid clogging issues
• • Rebuilt engines with upgraded guides and tensioners reset the reliability clock
• • High-mileage fleet 420d models often reach 200,000 miles with specialist care

Key points

• • Euro 6 B47D20A and B58B30A engines meet current MoT emissions limits
• • DPF and AdBlue systems must be functional and correctly calibrated post-installation
• • ECU remapping may be required to clear fault codes after engine swap
• • Retain all emissions certification paperwork for MoT tester verification if requested
• • Non-compliant engines risk MoT failure and potential ULEZ charge liabilities

Key points

• • Supply and fit removes coordination risks between parts supplier and local garage
• • xDrive and M4 variants require specialist calibration included in fitting package
• • Most installations complete within 2-3 working days from engine dispatch
• • Warranty coverage often extends to labour when using network-approved fitting centres
• • Post-installation road test and fault code clearance included as standard

Key points

• • VIN lookup reveals exact engine code, chassis generation and production date
• • Engine codes are stamped on the block near the oil filter housing
• • B47D20A replaced N47D20C in 420d models from late 2015 onwards
• • xDrive variants require additional transfer case compatibility verification during ordering
• • EngineMarket's registration tool instantly matches your variant to available rebuilt units