Most common 2021 BMW M340I problems
Share of the 11 complaints; one complaint can involve more than one system. "~" is the median mileage when the problem started.
BMW M340I complaints by model year
Best M340I years: 2021. Compare all years →
2021 BMW M340I recalls (6)
Electrical system › Software
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.
Remedy: Dealers will update the receiver audio module software, free of charge. Owner notification letters were mailed October 12, 2023. Owners may contact BMW customer service at 1-800-525-7417.
Seats
BMW of North America, LLC (BMW) is recalling certain 2019-2021 330i, 330i xDrive, M340i xDrive, 2020-2021 X3 sDrive30i, X3 xDrive30i, X3 M40i, X3M, 2021 X3 xDrive30e, X4 xDrive30i, and X4M vehicles. The seat frame may not have been welded properly to the seat rails.
Remedy: Dealers will replace the seat frame and back rest, free of charge. Owner notification letters were mailed May 22, 2023. Owners may contact BMW customer service at 1-800-525-7417.
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…
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.
Seat belts › Front › Buckle assembly
BMW of North America, LLC (BMW) is recalling certain 2021 330i, 330i xDrive, M340i, M3, and 330e xDrive vehicles. The bolt securing the seat belt assembly to the frame was not tightened to specification.
Remedy: BMW will notify owners, and dealers will inspect the front seat belt buckle assembly connection and, if necessary, replace it, free of charge. Owner notification letters were mailed on June 25, 2021.
Back over prevention › Software
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…
Remedy: BMW will notify owners, and dealers will inspect the rearview camera software and update it if necessary, free of charge. The recall began April 16, 2021. Owners may contact BMW customer service at 1-800-525-7417.
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.
Remedy: BMW will notify owners, and dealers will inspect the connection between the 48-Volt battery and the starter-generator assembly, replacing it if necessary, free of charge. The recall is expected to begin April 12, 2021.
NHTSA defect investigations
Federal safety investigators have looked into a possible defect involving the 2021 BMW M340I:
Pedestrian alert sounds
NHTSA received a petition on or about July 18, 2022, requesting that Federal Motor Vehicle Safety Standard (FMVSS) 141 be applied to all electric and hybrid vehicles operating in the United States. The petition can be reviewed at NHTSA.gov under ODI Number 11486072. FMVSS 141 establishes performance requirements for pedestrian alert sounds for motor vehicles.
What 2021 BMW M340I owners say
Engine & cooling
I have been smelling a burning odor in the vehicle for almost a year which the dealership and an independent shop had not been able to diagnose. The car was recently throwing Drivetrain Error codes which prompted a visit to the dealership. They found that the 48v battery and negative cable are burnt and quoted $5680 to replace the battery and cables. After investigating I found that there were recalls for this issue on other BMWs, including the same year and model of my vehicle, but my VIN is not pulling up a recall. The issue is a fire risk and a very expensive repair that should be covered by the manufacturer due to a known defect.
At approximately 20,000 miles, vehicle indicated excessively low oil. The dealer indicated oil level was excessively low but did not identify the problem,. The vehicle was filled and returned to owner. Within 1000 miles, the incident occurred again. Dealer replaced replaced the valve cover claiming that was the issue. Now within +/- 1000 miles, the oil level is again excessively low. I happen to have another identical BMW of the same year and same mileage having exactly the same problem (filing separate complaint).
Transmission & drivetrain
The contact owns a 2021 BMW M340I. The contact stated while driving various speeds, the vehicle independently shifted from reverse(R) to drive(D) to park(P). The contact stated that while driving approximately 10 MPH and attempting to stop the vehicle, the brake pedal was depressed and went to the floorboard. The contact stated that the brake failed to operate as designed. The vehicle was towed to a dealer who diagnosed that the vacuum pump needed to be replaced. The vehicle was repaired. The contact stated that an unknown transmission repair was performed. The manufacturer was made aware of the failure. The approximate failure mileage was 4,000.
Here's a strong version that sounds frustrated but still credible and harder to dismiss: I've owned many vehicles over the years, and this BMW has been, without question, the most problematic car I've ever had. The list of issues has been absurd for a vehicle in this price range and from a brand that markets itself as a premium luxury manufacturer. The sunroof failed, I've had multiple tire blowouts under normal driving conditions, the drive bar/suspension was bent from what should have been a routine road bump, the engine oil housing/component failed, and now I'm dealing with coolant system and drivetrain problems as well. At this point, it feels like one major issue after another. I expected quality, reliability, and engineering excellence from BMW, but my experience has been the complete opposite. Instead, ownership has been stressful, expensive, and incredibly disappointing. …
2021 BMW M340I engines & fuel economy
| Engine | Transmission | Drive | MPG city / hwy / combined |
|---|---|---|---|
| 3.0L 6-cyl turbo hybrid | 8-speed automatic | RWD | 23 / 32 / 26 |
EPA ratings. Class: Compact car.
Frequently asked questions
Is the 2021 BMW M340I a good car?
Based on 11 owner complaints filed with NHTSA, the 2021 M340I rates average: 23% fewer complaints than a typical year of the M340I at the same age. It is one of the best M340I years by this measure. Complaint counts don't account for sales volume or individual maintenance, so have any used car inspected before buying.
What is the most common problem with the 2021 BMW M340I?
The engine & cooling — 7 complaints, 64% of all complaints for this model year. Next are the transmission & drivetrain (3) and electrical system (2).
How many recalls does the 2021 BMW M340I have?
There are 6 recalls for the 2021 BMW M340I, the most recent from August 16, 2023 (software). Recall repairs are free at any authorized dealer — check whether yours has been done with the VIN recall check.
What are the best and worst years of the BMW M340I?
The best years by complaints, compared at the same age, are 2021. See the full BMW M340I years comparison.
At what mileage do 2021 BMW M340I problems happen?
The median mileage reported in complaints is about 4,000 miles; 100% of problems with a recorded mileage started before 50,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.