P0017 on BMW

The N20 four-cylinder engine in the 1 Series is prone to premature timing chain stretch and guide failure, particularly in models built before 2015. The plastic chain guides become brittle over time and can break apart, allowing chain slack that leads to jumped timing. This can cause catastrophic engine damage if the chain skips enough teeth.

The N20 2.0L turbocharged engine in 228i models (2014-2016) suffers from premature timing chain stretch and guide failure, typically between 40,000-80,000 miles. The single-row timing chain design is inadequate for the engine's power output. Chain stretch causes timing to jump, leading to rough running, poor performance, and potential catastrophic engine damage if the chain breaks. BMW issued a class action settlement covering 8 years/100,000 miles. This is identical to the N20 timing chain issue affecting 328i, 428i, X3, and other N20-powered models.

The N20 2.0-liter turbo engine in F30 3 Series 320i and 328i models (2012-early 2015) has a CRITICAL design defect in the plastic timing chain guides. The guides crack, degrade, and break apart due to material defects, causing the timing chain to skip or break. This results in catastrophic piston-to-valve collision and complete engine destruction requiring $8,000-$15,000 replacement. Early symptoms include rattling on cold start (like marbles in a tin can) and high-pitched whining between 1,500-2,500 RPM. BMW redesigned the guides in January 2015, but 2012-2014 models are ticking time bombs. Bimmerpost forums are full of catastrophic N20 failures. This is the WORST BMW reliability issue of the 2010s.

The 428i models equipped with the N20 four-cylinder turbo engine suffer from the same timing chain guide failure as other N20-powered BMWs. The plastic chain guides crack and disintegrate, allowing chain slack that leads to timing correlation faults and potential engine damage. The 2014-2015 model years are most affected, with BMW implementing updated guides in later 2015 production.

The N20 2.0L turbocharged engine in 428i models suffers from premature timing chain stretch and guide failure, typically occurring between 40,000-80,000 miles. The single-row timing chain design is inadequate for the engine's power output. Chain stretch causes the timing to jump, leading to rough running, poor performance, and potential catastrophic engine damage if the chain breaks. BMW issued a class action settlement covering 8 years/100,000 miles. This is identical to the N20 timing chain issue in 328i/X3/X5 models using the same engine.

The N20 2.0-liter turbo engine in F10 528i (2012-early 2015) has a CRITICAL design defect in plastic timing chain guides identical to F30 328i issue. The guides crack, degrade, and break apart from material defects, causing timing chain to skip or break, resulting in catastrophic piston-to-valve collision and complete engine destruction requiring $8,000-$15,000 replacement. Early symptoms include rattling on cold start (like marbles in tin can) and high-pitched whining between 1,500-2,500 RPM. BMW redesigned guides in January 2015, but 2012-2014 models are ticking time bombs. This is BMW's WORST reliability disaster of 2010s according to Bimmerpost. Failure rate estimated at 15-20% of all 2012-2014 N20 engines. Class action settlement provides some extended warranty coverage.

The N63 twin-turbo V8 engine suffers from TWO catastrophic design flaws that make it one of BMW's least reliable engines. First, the timing chain guides and tensioners degrade from excessive heat in the "hot-V" design (turbos mounted between cylinder banks). Plastic guides crack and fail by 80,000-100,000 miles, causing timing chain skip and catastrophic piston-to-valve collision ($8,000-$15,000 engine replacement). Second, valve stem seals cook from extreme turbo heat, causing excessive oil consumption (1 quart per 600-800 miles). The seals harden and crack, allowing oil into combustion chambers. BMW extended warranty to 10 years/120,000 miles for 2009-2015 models and released N63 Customer Care Package with updated parts, but 2006-2008 and 2016+ models not covered. Bimmerpost consensus: N63 is BMW's worst reliability disaster, avoid unless under warranty. Affects E60 550i (2006-2010), F10 550i (2011-2016), G30 M550i (2017-2023).

The N63 4.4L twin-turbo V8 engine in F12/F13 650i (2012-2018) suffers from premature timing chain stretch and plastic chain guide disintegration caused by the "hot-vee" turbocharger placement (turbos mounted between the cylinder banks). The extreme heat from the turbochargers accelerates degradation of the plastic timing chain guides, which become brittle and can shatter. When the guides fail, the timing chain can jump timing, causing catastrophic piston-to-valve collision and complete engine destruction ($15,000-25,000). BMW issued Technical Service Bulletin SIB 11 16 14 and the N63 Customer Care Package B001314 providing extended warranty coverage for some affected vehicles. Chain stretch is detectable via cold start rattling ("marbles in a tin can" sound) and timing-related diagnostic codes.

The N63TU3 4.4L twin-turbo V8 in M850i models uses plastic timing chain guides that wear prematurely under the extreme heat and stress of the hot-V configuration. As the plastic guides wear, the timing chain develops slack, causing rattling on cold starts and eventually risking timing chain skip or failure. Chain skip causes piston-to-valve collision and catastrophic engine destruction ($15,000-$25,000 replacement). While the N63TU3 has improved guides over earlier N63 versions, the fundamental plastic guide material still degrades from heat cycling. Turner Motorsport offers a complete timing chain guide kit (11317594899KT) with all necessary components. Bimmerpost consensus: replace timing chain guides preventively at 80,000-100,000 miles on N63TU3 engines before catastrophic failure.

The BMW B38 1.5L 3-cylinder turbocharged engine in the i8 develops turbocharger and timing chain issues at higher mileages (70,000+ miles). The turbocharger can develop oil leaks from the turbo oil feed/return lines and bearing seal degradation. Carbon buildup on intake valves is significant due to direct injection, requiring walnut blasting every 40,000-60,000 miles. The timing chain is marketed as "lifetime" but reports of chain stretch and noisy timing components increase on higher-mileage examples, especially those driven with extended oil change intervals. The B38 in the i8 operates differently than in a Mini or 1 Series due to the hybrid system - the engine doesn't run continuously, which can cause condensation and oil dilution from short run cycles.

The M2 Competition shares the S55 engine with M3/M4 and inherits the catastrophic crank hub failure issue. The crank hub (harmonic balancer) is press-fit onto the crankshaft and can slip under high load, especially with upgraded software or track use. When the hub slips, timing is lost and valves contact pistons, destroying the engine. This is the same critical failure point as the F80 M3 and F82 M4. The OEM crank hub has inadequate interference fit. Most failures occur on tuned cars or during hard track use between 30,000-70,000 miles.

The BMW S55 twin-turbo inline-6 engine has a critical design vulnerability where the crank hub is secured only by a single bolt with friction material - no keyway or mechanical lock. Under high load conditions such as aggressive downshifts, hard acceleration, or increased boost from tuning, the crank hub can slip. When this occurs, camshaft timing is thrown off and can cause catastrophic engine damage.

The F82 M4 S55 twin-turbo engine is prone to crank hub bolt loosening, the most well-known S55 failure mode. The factory stretch bolt can back out under repeated thermal cycling and high-RPM use, causing the crank timing to shift and potentially destroying the engine. This is the #1 preventative fix for any S55-equipped BMW.

Aging E39 M5 engines can suffer from brittle timing chain guides and weakening chain tension components, especially at higher mileage. Owners report startup chain slap, persistent front-engine rattling, and concern over guide fragmentation contaminating the oil system. While not every S62 fails this way, it is a documented high-cost issue in the E39 M5 community because neglected guide wear can lead to timing errors and severe engine damage.

The N20 turbocharged four-cylinder in E84 X1 models is prone to premature timing chain guide wear and failure. Plastic chain guides become brittle and can break, causing chain slack, jumped timing, and potential catastrophic engine damage. Most failures occur between 60,000-100,000 miles.

The N20 2.0L turbocharged engine in 2013-2015 X1 models suffers from premature timing chain stretch and guide failure, typically between 40,000-80,000 miles. The single-row timing chain design is inadequate for the engine's power output and torque. Chain stretch causes timing to jump, leading to rough running, poor performance, and potential catastrophic engine damage if the chain breaks. BMW issued a class action settlement covering 8 years/100,000 miles. This is identical to the N20 timing chain issue in 328i, 428i, and other N20-powered models.

The F25 X3 with the N20 engine shares the well-documented timing chain guide failure issue. Plastic guides wear prematurely and can break apart, causing catastrophic chain derailment and engine damage. This is the most critical known issue for N20-equipped X3 models.

The N20 2.0-liter turbo engine in F25 X3 xDrive28i (2012-early 2015) has a CRITICAL design defect in plastic timing chain guides identical to 3 Series/5 Series N20 issue. The guides crack, degrade, and break apart from material defects, causing timing chain to skip or break, resulting in catastrophic piston-to-valve collision and complete engine destruction requiring $15,000-$22,000 replacement. BMW issued multiple TSBs and a class action lawsuit was settled in 2021 over this widespread defect - eligible owners can receive up to $7,500 reimbursement for engine replacement or $3,000 for timing chain module repair. Early symptoms include rattling on cold start (like marbles) and high-pitched whining between 1,500-2,500 RPM. BMW redesigned guides in January 2015. This is BMW's WORST reliability disaster of 2010s. Failure rate estimated at 15-20% of all 2012-2014 N20 engines.

The F26 X4 equipped with the N20 engine suffers from the same timing chain guide failure that affects all N20-powered BMWs. The plastic chain guides deteriorate and can fracture, leading to chain slack and potential engine destruction. Failure typically occurs between 50,000-90,000 miles.

The N20 2.0L turbocharged engine in 2015-2016 X4 xDrive28i models suffers from premature timing chain stretch and guide failure, typically between 40,000-80,000 miles. The single-row timing chain design is inadequate for the engine's power output. Chain stretch causes timing to jump, leading to rough running, poor performance, and potential catastrophic engine damage if the chain breaks. BMW issued a class action settlement covering 8 years/100,000 miles. This is identical to the N20 issue affecting all N20-powered BMW models including X3, 3/4 Series, and X1.

N63 4.4L twin-turbo V8 engines in E70/F15 xDrive50i (2008-2018) suffer from wastegate rattle and eventual turbocharger failure. The wastegate flapper jiggles within mounting points against turbo housing due to worn bushings, most noticeable at idle or when letting off throttle. This leads to wastegate actuator failure, loss of power, increased turbo lag, and eventually complete turbo failure requiring replacement of BOTH turbos ($4,000-$8,000). Some vehicles may qualify for BMW N63 warranty extension programs (N63 CCP - Central Cooling Pump campaign). This compounds the N63 timing chain issue - 2008-2014 xDrive50i models have BOTH catastrophic timing chain AND wastegate/turbo failures. X5Forum consensus: avoid N63 models unless under warranty or budget $10,000+ for preventive repairs.

The N63 4.4L twin-turbo V8 engine in E70/F15 xDrive50i (2008-2018) and early G05 xDrive50i/M50i (2019-2021) has premature timing chain stretch and guide wear, causing catastrophic engine damage. BMW produced N63 engines between 2008-2014 with defective timing chain tensioners and guides made from weak materials. Timing chains stretch, guides crack and break, leading to rattling on cold start and potential timing failure causing piston-to-valve collision and complete engine destruction ($15,000-$25,000 replacement). BMW issued service bulletins and extended warranties for some affected vehicles. 2015+ N63TU (Technical Update) engines have improved timing components but still require monitoring. This is same catastrophic N63 issue affecting 5 Series 550i. Bimmerpost consensus: avoid 2008-2014 N63 models unless timing chain has been replaced with updated parts.

The N63 4.4L twin-turbo V8 engine in E71 (2008-2014) and F16 (2015-2018) X6 xDrive50i models suffers from premature timing chain stretch and guide failure. This is the same catastrophic issue affecting X5 xDrive50i. The plastic timing chain guides disintegrate from the extreme heat generated by the "hot-vee" turbocharger configuration where turbos sit between the cylinder banks. Timing chains stretch, guides crack and break, leading to chain jump or failure causing piston-to-valve collision and complete engine destruction ($15,000-25,000 replacement). BMW issued TSB B001314 in 2014 acknowledging the issue. Bimmerpost consensus: avoid 2008-2014 N63 models unless timing chain has been replaced with updated parts.