2021 BMW M440I Problems
Owner-reported complaints filed with NHTSA, grouped by component
Data refreshed
What this page shows
Everything below is an owner-reported complaint submitted to NHTSA about the 2021 BMW M440I, grouped by the component NHTSA recorded on the report. These are not confirmed defects, and they are not recalls. NHTSA does not verify most reports before publishing them, and a category with more reports in it is not evidence that a part is defective.
Complaints are reports submitted by owners and drivers to NHTSA. They are not verified and do not establish that a defect exists.
Reports by component
Ranked by how many owner reports name each component category
- Engine225.0%
- Driver assistance112.5%
- Electrical112.5%
- Brakes112.5%
- Interior & seats112.5%
- Powertrain (other)112.5%
- Seat belts112.5%
Percentages are of component mentions. A single complaint can name more than one component, so these do not sum to the total complaint count.
Each component in detail
What the reports in each category say, in the owners' own words
Engine
Reports naming the engine itself — including stalling, misfires, oil consumption, cooling and internal engine components.
From owner reports, verbatim
The engine starter motor system failed, specifically involving an intermittent no-start condition related to a pinion starter line break / internal component defect. The vehicle and all original mechanical components are fully intact and available for professional inspection upon request. The engine starter motor system failed, specifically involving an intermittent no-start condition related to a pinion starter line break / internal component defect. The vehicle and all original mechanical components are fully intact and available for professional inspection upon request. The vehicle is currently experiencing these active symptoms. The vehicle experiences sudden, unpredictable intermittent no-start scenarios. Being unable to dependably start or restart the engine creates a severe risk of stranded occupants in hazardous traffic scenarios, remote areas, or extreme weather conditions. Furthermore, this failure pattern matches identical 2026 BMW starter recalls where internal mechanical wear creates a severe overheating condition and an elevated vehicle fire risk, directly threatening passenger safety. No, the component has not yet been formally inspected by the manufacturer, police, or insurance representatives since it has not resulted in an active collision or fire. It has only been scanned for diagnostic error codes. The symptoms are intermittent no-start events that happen unexpectedly from a complete stop. Diagnostic system scans revealed software errors specifically pointing to fault code XXX indicating a line break in the pinion starter. These symptoms first began appearing intermittently earlier this year. VIN: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
The car basically blew up on the highway at rush hour. BMW knows of this issue with this model and has some of their other models under a recall for this very thing. I have a service action from BMW saying that the water pump assembly needs to be fixed before this very problem occurs but for some reason even though our model is on the service report it isn't on the recall list nor was this part replaced as instructed even though the vehicle has always been service at a BMW dealership. It was very dangerous as their were flames and burning hot coolant and shards of metal shooting everywhere as my son was on the highway being passed by big trucks. Weren't going too fast as we were just getting on the highway merging in which was also dangerous as everyone else was going fast. BMW has given me the runaround from department to department on this even though they all seem to agree that mine should be part of the recall or already fixed which was obvious because the new part is made of a different material than the old original part. On their service action my car is the G22 series clearly listed
Too few reports in this category for a page of its own — they appear in the full complaint list.
Driver assistance
Reports naming forward-collision avoidance, lane keeping, back-over prevention, cruise control and related electronic driver-assistance systems.
From owner reports, verbatim
I am seeing a lot of concerns regarding the seatbelt extenders, the buckle end pretensioner, seat wiring harness and the yellow box connectors that are where the main power and air bag SRS connections sit under the drivers seat. The seat harnesses are catching in the sliding track mechanism during forward and backward adjustments, isn't that a manufacturer error as the harnesses are only kept in place by plastic routing clips, which may or may not be there. I am just wondering if this should be looked at on the 2021 440i convertibles? I love the car but worry this is a safety issue forums are mentioning. Car alarms 1m-4am is that software updates, went on for four days in June.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Electrical
Reports naming the electrical system — wiring, battery, charging, control modules, infotainment and electrical accessories.
From owner reports, verbatim
The engine starter motor system failed, specifically involving an intermittent no-start condition related to a pinion starter line break / internal component defect. The vehicle and all original mechanical components are fully intact and available for professional inspection upon request. The engine starter motor system failed, specifically involving an intermittent no-start condition related to a pinion starter line break / internal component defect. The vehicle and all original mechanical components are fully intact and available for professional inspection upon request. The vehicle is currently experiencing these active symptoms. The vehicle experiences sudden, unpredictable intermittent no-start scenarios. Being unable to dependably start or restart the engine creates a severe risk of stranded occupants in hazardous traffic scenarios, remote areas, or extreme weather conditions. Furthermore, this failure pattern matches identical 2026 BMW starter recalls where internal mechanical wear creates a severe overheating condition and an elevated vehicle fire risk, directly threatening passenger safety. No, the component has not yet been formally inspected by the manufacturer, police, or insurance representatives since it has not resulted in an active collision or fire. It has only been scanned for diagnostic error codes. The symptoms are intermittent no-start events that happen unexpectedly from a complete stop. Diagnostic system scans revealed software errors specifically pointing to fault code XXX indicating a line break in the pinion starter. These symptoms first began appearing intermittently earlier this year. VIN: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Too few reports in this category for a page of its own — they appear in the full complaint list.
Brakes
Reports naming service brakes, the antilock braking system, brake hoses, master cylinders or the parking brake.
From owner reports, verbatim
Vehicle brakes malfunctioned.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Interior & seats
Reports naming seats, latches, locks, linkages and interior fittings.
From owner reports, verbatim
I am seeing a lot of concerns regarding the seatbelt extenders, the buckle end pretensioner, seat wiring harness and the yellow box connectors that are where the main power and air bag SRS connections sit under the drivers seat. The seat harnesses are catching in the sliding track mechanism during forward and backward adjustments, isn't that a manufacturer error as the harnesses are only kept in place by plastic routing clips, which may or may not be there. I am just wondering if this should be looked at on the 2021 440i convertibles? I love the car but worry this is a safety issue forums are mentioning. Car alarms 1m-4am is that software updates, went on for four days in June.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Powertrain (other)
Powertrain reports that are not specifically the engine or transmission — driveshafts, axles, transfer cases and differentials.
From owner reports, verbatim
BMW dealer noted "clunk on accel" at 57,152 miles on RO #224018 under engine mounts. Dealer quoted $3,463.38 for engine mounts. I declined repair. Clunk on acceleration is still present at 60,700 miles. Same symptom as BMW Service Bulletin SIB 27-02-20 for 4 Series Drive jerking/shuddering from transfer case. Transfer case was serviced by non-BMW shop prior to my ownership (unknown fluid spec). Dealer documentation only notes clunk on accel and engine mounts/alignment. Requesting investigation as this matches known transfer case defect with lifetime fluid claim. Vehicle is just out of 4yr/50k warranty.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Seat belts
Reports naming seat belts, buckles, retractors and pretensioners.
From owner reports, verbatim
I am seeing a lot of concerns regarding the seatbelt extenders, the buckle end pretensioner, seat wiring harness and the yellow box connectors that are where the main power and air bag SRS connections sit under the drivers seat. The seat harnesses are catching in the sliding track mechanism during forward and backward adjustments, isn't that a manufacturer error as the harnesses are only kept in place by plastic routing clips, which may or may not be there. I am just wondering if this should be looked at on the 2021 440i convertibles? I love the car but worry this is a safety issue forums are mentioning. Car alarms 1m-4am is that software updates, went on for four days in June.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Higher-selling and older vehicles accumulate more reports. Counts are not failure rates and are not directly comparable between vehicles that sold in very different numbers.
Elsewhere on this vehicle
Data sources
- NHTSA Office of Defects Investigation — owner-reported complaints and the components recorded on them
Data on this page last refreshed .