BMW · Known Issues
2020 BMW M340i Problems: 21 Known Issues
2020 model year · 1,250+ owner reports · Updated September 2026
2020 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
2020 model year · 1,250+ owner reports · Updated September 2026
2020 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
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According to Au7o's analysis of 1,250+ owner reports, the 2020 BMW M340i has 21 documented known issues, with 8 rated critical. The most serious are Coolant Loss from Expansion Tank and Water Pump ($400-$1,200 repair), High-Pressure Fuel Pump (HPFP) Failure ($600-$1,500 repair), 2020 M340i Brake-Assist Recall 21V-598, 2019-2022 M340i Seat-Belt Warning Recall 23V-584, Mechanical Coolant Pump Pulley Fracture Throws Drive Belt (SIB 11 05 21 Service Action) ($0-$1,500 repair), Steering Gear Tie Rod Fracture Recall 20V-355 (2019-2020 Builds) ($0-$0 repair), B58TU Variable-Displacement Oil Pump Failure (Plastic Internal Component, Early Builds) ($2,000-$3,500 repair) and Front Seat Frame Improperly Welded - Recall 23V-211 (Nov 2019 - May 2021 Builds) ($0-$0 repair). The most commonly reported issue is Coolant Loss from Expansion Tank and Water Pump with 380 owner reports. Across all issues with published estimates, repair costs range from $50 to $4,000. DIY maintenance guides at au7o.io.
ELECTRICAL SYSTEM:BODY CONTROL MODULE:SOFTWARE
BMW of North America, LLC (BMW) is recalling certain 2023 330i, 330i xDrive, M340i, M340i xDrive, M3, 330e, 330e xDrive, 430i Convertible, 430i xDrive, M440i, 2022-2023 430i, 430i xDrive, M440i xDrive, i4 eDrive40, and i4 M50 vehicles. During a service visit, a replacement electronic control unit (ECU) may have been installed with incorrect programming, which can cause the automatic door locking (ADL) function to not lock the doors as intended.
SEAT BELTS
BMW of North America, LLC (BMW) is recalling certain 2019-2022 330i, 330i xDrive, M340i, 2022 430i Coupe, 2021-2022 430i, M440i Convertible, and 2020-2022 228i xDrive Gran Coupe vehicles. The receiver audio module control unit software may fail to properly generate audible seat belt warnings to the driver to fasten their seat belt. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 208, "Occupant Crash Protection."
SEAT BELTS
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."
ELECTRICAL SYSTEM:12V/24V/48V BATTERY
BMW of North America, LLC (BMW) is recalling certain 2021 M340i xDrive, M440i xDrive Coupe, 530i, 530i xDrive, 540i, 540i xDrive, 740Li, 740Li xDrive, 840i Gran Coupe, 840i xDrive Gran Coupe, X5 sDrive40i, X5 xDrive40i, X6 sDrive40i, X6 xDrive40i, and X7 xDrive40i vehicles. The connection between the 48-Volt battery and the starter-generator may not have been assembled properly, which can cause increased electrical resistance at the connections.
BACK OVER PREVENTION: SENSING SYSTEM: CAMERA
BMW of North America, LLC (BMW) is recalling certain 2019-2021 X3 sDrive30i, X3 xDrive30i, X3 M40i, X3M, X4 xDrive30i, X4 M40i, M550i, X4M, X5 sDrive40i, X5 xDrive40i, X5 xDrive50i, X5M, X5 M50i, X7 xDrive40i, X7 xDrive50i, X7 M50i, Alpina XB7, 330i, 330i xDrive, M340i, M340i xDrive, and 8 Series Coupe, Convertible and Grand Coupe, 840i, 840i xDrive, M850i xDrive, M8, 2020-2021 530e, 530e xDrive, 330e, 330e xDrive, 745Le, 745Le xDrive, X5 xDrive45e, X3 xDrive30e, X6 sDrive40i, X6 xDrive40i, X6 xDrive50i, X6 M50i, X6M, 530i, 530i xDrive, 540i, 540i xDrive, M550i xDrive, M5, 740i, 740Li, 740Li xDrive, M760i Drive, M760Li xDrive, 750Li xDrive Alpina, Alpina B7 xDrive, and 2021 4 Series Coupe 430i, 430i xDrive, M440i xDrive vehicles. When shifting into Reverse, a small portion of the rearview image may be obscured, or the screen may not illuminate. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 111, "Rear Visibility."
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According to Au7o's analysis of 1,250+ owner reports, the 2020 BMW M340i has 21 documented issues. The most frequently reported are: Coolant Loss from Expansion Tank and Water Pump, High-Pressure Fuel Pump (HPFP) Failure, 2020 M340i Brake-Assist Recall 21V-598. Of these, 8 are rated critical and should be addressed promptly.
The 2020 BMW M340i has 21 known issues documented across 1,250+ owner reports. 8 issues are rated critical: Coolant Loss from Expansion Tank and Water Pump and High-Pressure Fuel Pump (HPFP) Failure and 2020 M340i Brake-Assist Recall 21V-598 and 2019-2022 M340i Seat-Belt Warning Recall 23V-584 and Mechanical Coolant Pump Pulley Fracture Throws Drive Belt (SIB 11 05 21 Service Action) and Steering Gear Tie Rod Fracture Recall 20V-355 (2019-2020 Builds) and B58TU Variable-Displacement Oil Pump Failure (Plastic Internal Component, Early Builds) and Front Seat Frame Improperly Welded - Recall 23V-211 (Nov 2019 - May 2021 Builds). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known BMW M340i issues range from $0 to $4,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Coolant Loss from Expansion Tank and Water Pump, typically costs $400-$1,200 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
The M340i's B58 engine experiences the same coolant loss issues as other B58-powered BMWs, but the M340i's higher sustained performance driving tends to accelerate the problem. The plastic coolant expansion tank develops hairline cracks from heat cycling, and the electric water p… Repairs typically run $400-$1,200. Severity: high.
The B58 engine's high-pressure fuel pump can fail, though at lower rates than the older N54 engine. When the HPFP fails, fuel pressure drops below the minimum required for proper direct injection, causing long cranking, rough idle, misfires, and in severe cases, the engine stalli… Repairs typically run $600-$1,500. Severity: high.
NHTSA campaign 21V-598 covers certain model-year 2020 BMW M340i and M340i xDrive vehicles. During engine start, engine-management software can command the combined oil/vacuum pump in a way that damages it, reducing or eliminating vacuum brake assistance. Full mechanical braking r… Severity: high.
BMW SIB 65 23 23 and NHTSA campaign 23V-584 cover certain model-year 2019-2022 G20 M340i vehicles. Receiver Audio Module software may delay or fail to generate the audible driver seat-belt warning, causing noncompliance with FMVSS 208 and increasing injury risk if a driver relies… Severity: high.
On B58 cars built between September 2020 and May 24, 2021 (MY2020-2021 M340i/M340i xDrive, also G22 M440i, G30 540i, X5/X6/X7 40i), the belt pulley on the mechanical coolant pump can fracture. When it lets go the serpentine belt comes off the coolant pump and alternator, so the e… Repairs typically run $0-$1,500. Severity: high.
On early G20 M340i and M340i xDrive sedans (and the B58-powered Toyota Supra built alongside them), the steering-gear tie rods could be damaged under a combination of high ambient temperature and rough road surfaces, and a damaged rod could fracture, causing loss of steering cont… Repairs typically run $0-$0. Severity: high.
The second-generation B58 (B58TU) fitted to 2019-2020 M340i uses a variable-displacement oil pump whose pressure-regulating adjuster was made of thermoplastic. On cars built up to roughly mid-2020 the plastic component can crack, producing incorrect (high or low) oil pressure, a… Repairs typically run $2,000-$3,500. Severity: high.
Certain 2019-2021 BMW 3 Series (including M340i/M340i xDrive), X3 and X4 vehicles produced between November 15, 2019 and May 8, 2021 received driver and/or front passenger seat frames that the supplier did not weld to specification at the rail joint. An improperly welded frame ma… Repairs typically run $0-$0. Severity: high.
As a direct-injection engine, the B58 in the M340i does not have fuel washing over the intake valves, leading to gradual carbon deposit buildup on the valve backs. Oil vapors from the crankcase ventilation system deposit carbon that restricts airflow and reduces performance. Symp… Repairs typically run $400-$800. Severity: medium.
The B58 engine has a documented tendency for paper oil filters to shred and break apart during normal use. As oil passes through the filter under pressure, the filter media can separate from the end caps and tear into multiple pieces. Shredded filter material can deposit paper fr… Repairs typically run $50-$200. Severity: medium.
Owners report harsh or jerky shifts from the ZF 8-speed automatic, most noticeable on the 1-2 and 2-3 changes at low speed before the drivetrain is warmed up, and aggravated by Sport mode in cold stop-and-go traffic. The ZF 8HP is sensitive to fluid condition; degraded or low flu… Repairs typically run $350-$2,500. Severity: medium.
The rubber valve-cover gasket and the oil filter housing gasket on the B58 inline-six harden and crack from repeated heat cycling, allowing engine oil to seep out. It typically appears from roughly 60,000-100,000 miles. Leaking oil can drip onto hot exhaust components (burning sm… Repairs typically run $400-$900. Severity: medium.
M340i owners report the 12V AGM battery discharging or dying, sometimes on relatively young cars, often triggered by short-trip driving, parasitic drains from modules not entering sleep mode, or a failing Intelligent Battery Sensor (IBS). German owners on motor-talk specifically… Repairs typically run $300-$700. Severity: medium.
The B58 uses VANOS (variable valve timing) solenoids whose internal rubber O-rings degrade from heat and oil contamination, and the solenoid electronics can fail over time. A leaking O-ring lets oil pass where it should not and disrupts cam-timing control, producing rough running… Repairs typically run $200-$600. Severity: medium.
Separate from the fracture recall, a large number of G20 M340i owners report a knocking, cracking, or creaking noise from the front axle at low speed over bumps and expansion joints, often felt through the steering wheel and worse in warm weather. Dealers commonly replace lower c… Repairs typically run $0-$4,000. Severity: medium.
Two software recalls hit the G20 M340i's rear-view camera under FMVSS 111. 19V-684 (Sept 2019, 257,473 BMW/Supra vehicles incl. 2019-2020 M340i) let the driver adjust the camera/display settings so that the rear image was no longer shown, and the car remembered the setting. 21V-0… Repairs typically run $0-$0. Severity: medium.
The B58 engine's electronic wastegate actuator can develop play over time, producing a characteristic rattling or buzzing noise at idle and during deceleration. The wastegate flapper valve develops clearance within its housing, causing it to vibrate at certain RPMs. While often d… Repairs typically run $200-$2,000. Severity: low.
G20 sedans with the moonroof develop a rattle, ticking, or cracking noise from the roof over rough pavement and in heat, which many M340i owners describe as the single most annoying flaw in an otherwise quiet cabin. BMW addressed it with a service bulletin whose first step is to… Repairs typically run $0-$400. Severity: low.
The G20 M340i uses motorized upper and lower active air flaps behind the kidney grille to manage cooling and aerodynamics. The plastic linkage arms embrittle with heat cycles, slats snap or pop out of their mounts, and debris or ice jams the flaps and burns out the actuator, leav… Repairs typically run $0-$1,200. Severity: low.
The M340i's standard M Sport brakes (blue four-piston front calipers, semi-metallic pads) squeal loudly at low speed and light pedal pressure, especially in stop-and-go traffic and after the pads heat-cycle. It is one of the most repeated complaints on G20 forums and continues fr… Repairs typically run $0-$1,000. Severity: low.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.