The 2021 Z4 M40i with the B58 engine is generally solid, but the shared platform with Toyota Supra means it inherits some transmission cooling weaknesses and oil consumption quirks that emerge as these cars approach track use or higher mileage.
ZF 8HP Transmission Oil Cooler Failure
Occasional · high severity
Typical onset: 40,000-70,000 mi
Symptoms: Transmission overheat warnings on aggressive driving or track days, Limp mode activation after sustained high-speed driving, Burnt transmission fluid smell, Check engine light with trans temp codes
Fix: Replace transmission oil cooler and flush system. Requires front bumper removal and access from underneath. 4-6 hours labor depending on shop familiarity with platform.
Estimated cost: $1,200-2,000
B58 Oil Consumption / Piston Ring Issues
Rare · high severity
Typical onset: 30,000-80,000 mi
Symptoms: Burning more than 1 qt per 1,000 miles, Blue smoke on cold starts or deceleration, Fouled spark plugs in cylinders 4-6 most commonly, Low oil pressure warnings if ignored long enough
Fix: Early B58 gen had piston ring sealing concerns. Fix requires engine-out short block replacement or full teardown for new pistons and rings. 25-35 hours labor, plus machine work if cylinder honing needed. BMW extended warranty covered many early cases, but 2021s are borderline.
Estimated cost: $8,000-14,000
Transmission Mount Failure
Common · low severity
Typical onset: 50,000-90,000 mi
Symptoms: Clunk on aggressive 1-2 or 2-3 shifts, Vibration at idle in Drive, Driveline slop when switching from Drive to Reverse, Visible tearing or fluid weeping from mount
Fix: Replace transmission mount. Straightforward job with transmission support, 2-3 hours. Common wear item on spirited-driving examples.
Estimated cost: $400-700
High-Pressure Fuel Pump (HPFP) Failure
Occasional · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Long crank on hot starts, Intermittent misfires under boost, Fuel pressure fault codes (P0087, P228C), Limp mode with reduced power
Fix: Replace HPFP on back of cylinder head. Requires intake manifold removal for access. 4-5 hours labor. Some examples had contaminated fuel filter contributing, so replace filter at same time.
Estimated cost: $1,500-2,200
Coolant Thermostat Housing Leaks
Occasional · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Coolant smell in cabin or engine bay, Drips visible under front of engine, Low coolant warning light, Overheating if leak progresses unchecked
Fix: Replace thermostat housing and reseal. Common B58 weak point where plastic housing cracks at mounting points. 3-4 hours labor.
Estimated cost: $600-1,000
Soft-Top Micro-Switch Failures
Occasional · low severity
Symptoms: Convertible top refuses to operate despite full charge, Intermittent 'top not secure' warnings, Top stops mid-cycle and won't reset, Latch sensors showing false open/closed states
Fix: Diagnose and replace faulty micro-switches in latch mechanisms or roof motors. Labor-intensive because of trim removal and calibration. 2-4 hours depending on which switch.
Estimated cost: $500-1,200
Owner tips
Check transmission fluid condition every 30k mi if car sees track use — dark or burnt fluid means cooler is marginal
Monitor oil consumption religiously in first 50k mi; if burning more than 1 qt per 3k mi, document for potential warranty claim
Upgrade to higher-capacity transmission cooler if planning any track days or sustained mountain driving
Use top-tier fuel only; HPFP is sensitive to contamination and ethanol content above E15
Inspect coolant level monthly — B58 thermostat housing cracks give little warning before major leak
Buy a 2021+ with full service records and low oil consumption history; avoid high-mileage track cars unless trans cooler upgraded and compression-tested.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
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BMW of North America, LLC (BMW) is recalling certain 2021-2023 Toyota Supra, 2022-2023 2 Series Coupe, 2021-2024 5 Series (xDrive), 2021-2022 Z4, 2022-2024 4 Series (Gran Coupe), 2021-2024 4 Series (Convertible and xDrive Convertible), 2021-2023 4 Series (Coupe), 2021-2024 3 Series, 2021-2023 X4, 2021-2024 X3 vehicles. Please see the recall report for a complete list of all models. The engine starter may overheat and catch fire due to wear on an internal component.
Consequence: Fire increases the risk of injury.
Remedy: Dealers will replace the engine starter, free of charge. A letter informing owners of the safety risk was mailed on March 27, 2026. Owners will receive another letter once the remedy is available. Owners may contact BMW customer service at 1-800-525-7417 or Toyota's customer service at 1-800-331-4331. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning March 24, 2026.
BMW of North America, LLC (BMW) is recalling certain 2019-2021 BMW 330i, 2019-2022 BMW Z4, 2020-2022 BMW 530i, X3, X4, Toyota Supra, 2021-2022 BMW 430i, 430i Convertible, and 2022 BMW 230i vehicles. The engine starter relay may corrode, causing the relay to overheat and short circuit.
Consequence: A short circuit in the starter relay may increase the risk of a fire.
Remedy: Owners are advised to park their vehicles outside and away from structures until the remedy is complete. Dealers will replace the engine starter, free of charge. Owner notification letters were mailed February 6, 2026. Owners may contact BMW customer service at 1-800-525-7417. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning November 14, 2025.
ENGINE · 21V598000
2021-08-02
BMW of North America, LLC (BMW) is recalling certain 2020 M340i, M340i xDrive, 540i, 540i xDrive, X3 M40i, 2020-2021 X4 M40i, 745Le xDrive, 2019-2021 Z4 M40i, and 2020-2021 Toyota Supra vehicles. During engine start, the engine management software may cause loss of braking assist. Full mechanical braking (without assist) remains available.
Consequence: Loss of braking assist can increase the risk of a crash.
Remedy: Dealers will update the engine management software, free of charge. Owner notification letters were mailed on September 17, 2021. Owners may contact BMW customer service at 1-800-525-7417.
SEAT BELTS · 21V554000
2021-07-21
BMW of North America, LLC (BMW) is recalling certain 2021 2 Series (230i, 230i xDrive, M240i, M240i xDrive), 330e, 330e Xdrive, 4 Series Coupe (430i, 430i xDrive, M440i xDrive) M4 Coupe, M4 Competition Coupe, BMW 4 Series Convertible (430i, M440i), BMW X1 sDrive28i, xDrive28i, 2 Series Gran Coupe (228i, 228i xDrive, M235i xDrive), M2 Competition Coupe, 330i, 330i xDrive, M340i, M340i xDrive, M3, M3 Competition, 530i, 530i xDrive, 540i, 540i xDrive, MINI Hardtop 2 Door (Cooper, CooperS, JCW), X2 sDrive28i, X2 xDrive28i, X2 M35i, Z4 sDrive30i, Z4 M40i, MINI Hardtop 2 Door (Cooper SE), MINI Convertible (Cooper, Cooper S, JCW), MINI Clubman (Cooper S, Cooper S All4, JCW), MINI Countryman (Cooper, Cooper All4, Cooper S, Cooper S All4, JCW All4), Rolls Royce Ghost, MINI Countryman (Cooper S E All4), Rolls Royce Phantom, Rolls Royce Cullinan, and Toyota Supra vehicles. The passenger seat belt Automatic Locking Retractor (ALR) may deactivate early, before the webbing fully retracts. As such, these assemblies fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 208, "Occupant Crash Protection."
Consequence: During a crash, a seat belt retractor that does not function as intended increases the risk of injury.
Remedy: Dealers will inspect the seat belt retractors (including the seat belts) and, if necessary, replace the retractors, free of charge. Owner notification letters were mailed on September 3, 2021. Owners may contact BMW customer service at 1-800-525-7417; 1-866-825-1525 (MINI); 1-877-877-3735 (Rolls Royce); and 1-888-270-9371 (Toyota).
BMW of North America, LLC (BMW) is recalling certain 2020-2021 Z4 and 2020-2021 Toyota Supra vehicles. The weld between the fuel tank halves may have been insufficiently welded, causing the weld to fail.
Consequence: The failed weld may allow fuel to leak, increasing the risk of a fire in the presence of an ignition source.
Remedy: BMW will notify owners, and dealers will replace the fuel tank, free of charge. The recall began December 18, 2020. Owners may contact BMW customer service at 1-800-525-7417 or Toyota customer service at 1-888-270-9371.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.