2021 BMW X5: sudden loss of power

Filed Oct 7, 2026 · Transmission · NJ

Description of Safety Concern: I am writing to formally submit a vehicle safety complaint regarding the xDrive transfer case on my 2021 BMW X5. While driving, the vehicle exhibits noticeable hesitation, shuddering, and jerking during acceleration at lower speeds and when executing tight turns. This erratic power delivery creates a potential safety hazard, particularly when accelerating into traffic, merging onto highways, or pulling out from intersections, as the momentary loss of predictable drivetrain response increases the risk of a collision. Despite internal technical bulletins from the manufacturer (SI B27 02 20) acknowledging shuddering caused by transfer case clutch breakdown, no official safety recall has been issued. I request that the federal safety agency open an investigation into these xDrive transfer case failures to evaluate the safety risks posed by drivetrain hesitation and potential sudden power loss. Thank you for your attention to this safety issue.

Filed Sep 23, 2025 · Engine, Transmission · VA

Component Failed: Water pump (engine cooling system) - Part has been superseded by BMW with upgraded version, indicating manufacturer awareness of defect. Failed component retained and available for inspection upon request. Safety Risk: Complete water pump failure at 56,611 miles created immediate risk of catastrophic engine overheating and potential engine seizure while driving. BMW-certified mechanic warned that driving vehicle even short distances could result in total engine failure, creating risk of: Sudden loss of power on highways/intersections Engine fire from overheating Being stranded in dangerous locations/conditions Complete loss of steering assist if engine stops Confirmation: BMW-certified independent mechanic (formerly employed by BMW) confirmed water pump failure and identified it as "common B58 engine issue." BMW dealer (Silver Spring) immediately quoted exact repair cost of $2,300, indicating familiarity with this failure pattern. Mechanic documented that BMW has superseded the original part with an upgraded design, suggesting manufacturer acknowledgment of defect. Inspection Status: Failed part preserved by mechanic with full documentation including BMW's superseded part number from their system. Vehicle not inspected by BMW due to dealer network failure - three dealers failed to respond, one took 5+ hours to return call, none could provide service in reasonable timeframe. Warning Signs: No prior warning symptoms. Failure was sudden and catastrophic. Temperature gauge spiked without warning during normal driving conditions. No previous cooling system issues or warning lights. Regular maintenance performed per BMW specifications. Additional Pattern Evidence: Research reveals extensive documentation of identical B58 engine water pump failures between 40,000-60,000 miles across multiple BMW models (X5, X3, 3-series, 5-series) on owner forums. BMW's decision to supersede the part without issuing a recall suggests they are aware of the defect.

Filed Oct 20, 2023 · Transmission · MI

Drivetrain - A drivetrain malfunction message came-up a few weeks back on the high-way indicating “It is safe to drive but with reduced power” and the vehicle suddenly slowed down on the highway with less power to drive putting us in unsafe condition. The vehicle has less than 25,000 miles. The incident was reported to a BMW dealer for reporting to BMW and with a request for investigation and fixing prior to warranty expiration. Unknown - After a long drive (some times after a short drive) when the vehicle (PHEV) is parked and plugged-in, a loud noise can be heard. The noise goes away once its unplugged and locked. The incident was reported to a BMW dealer for reporting to BMW and with a request for investigation and fixing prior to warranty expiration.

Filed Jul 8, 2023 · Transmission · PA

While driving on highway/turnpike with cruise control on at 70 mph, drivetrain malfunction warning appeared and lost power. After turning off cruise control and playing around with buttons, could only get car to go about 35-40 mph, top speed with peddle to the floor. Very scary situation in traffic on busy highway. This happened twice about a month apart. First time, had to drive about 10+ miles in right lane with blinkers on to get to an exit. It was late at night and I didn't want to stop on my own. Once turned the car off and on a couple of time seemed to clear the error and I was able to drive city roads at minimal speed limit. Next day car was back to normal. Second time, drove about 2 miles to the exit with the blinkers on. This time when I restarted the car there was still not a lot of power. Drove for a bit but wasn't able to make it to speed limit of 45 mph. Made it home and turned car off again, next day it was okay. After restarting car a couple of times problem seems to go away. Took it to the dealer and all they did was "reset the system" which does not seem like anything is fixed. Will wait and see.

Filed Apr 3, 2023 · Electrical, Engine · CA

While driving about 60 mph on a freeway, the vehicle rapidly flashed several "advanced driver system failure" messages, lost all power and came to a stop. It was not possible to prevent the vehicle from rapidly decelerating even by depressing the accelerator all the way to the floor. The vehicle rapidly decelerated, forcing other drivers behind to swerve to avoid a crash.

Filed Dec 26, 2021 · Transmission · VA

Unknown car started shaking on the highway and suddenly lost power. Shown error 'power train mailfunction'

Filed Oct 7, 2021 · NY

Drive train warning displayed then power loss and stalling occurred on highway

Filed Jul 7, 2021 · Brakes · PA

On 6/8/2021, when pulling out of my driveway approximately 9:00 am, I experienced the car switching from Hybrid mode to Sport mode without me engaging the Sport mode control. The following day (6/9/2021), after a day of primarily interstate driving (over 200 miles), while stopping at a red light, I felt the brake pedal fall to the floor faster than I was applying pressure and I came to a sudden stop. The brakes had seized and the car was towed to Thompson BMW. The tow driver was able to release the brakes by pulling up the brake pedal. Thompson BMW could not recreate the brake failure but their diagnostics indicated brake failure. BMW NA was called as my car was less than 6 months old with 9724 miles. The service advisor told me that they were instructed to replace the Master Cylinder but could not tell me why brakes failed. Knowing that this was a significant safety concern, I opened a safety complaint with BMW. BMW could not tell me the root cause of the brake failure and as a result, I had no confidence that the problem was “fixed”. Master cylinders rarely fail. They also refused to provide me the diagnostics report. They said I was only entitled to the maintenance invoice. Linda Vitale was assigned my complaint and in a voicemail, told me I lost power to the DSCI module. She said the DSCI “has a fail-safe mode and if no power was present the conventional brakes” would work. They replaced the DSCI module and “it should be fine.” Based on her email, and then conversation, BMW engineering said I had an electrical issue. So why did the conventional brakes fail? I am very concerned that BMW has not identified the real problem and I can experience this brake failure again. If this failure had occurred while braking on an interstate highway, I could have been killed or vehicle could have caused fatal accident. I am extremely concerned about the safety of this vehicle, especially since over 60% of my driving in on highways and interstates.

Filed Apr 28, 2021 · Fuel system, Transmission · 7,500 miles · NJ

Drove at the speed of 75 MPH in the highway all in a sudden the car lost power until its speed dropped to 62 MPH. It is a hybrid. Dash board showed some reserved battery power and half tank of gasoline. It is a big safety issue. Need to find the cause of it.