2021 BMW M340I Owner Complaints

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.

NHTSA ID

11747887

Incident

Jul 1, 2026

The BMW B58TU oil pump thermoplastic component issue that can cause catastrophic failure to the engine. The the gen 1 oil pump was made from plastic and after issues were discovered, they switched to metal oil pumps. However this known issue is something that BMW has not addressed in the models 2019-2021 that came with the inferior oil pump.

NHTSA ID

11747283

Incident

Jun 29, 2026

I am reporting a safety concern involving BMW vehicles equipped with the B58 Technical Update (B58TU) engine, commonly found in model years 2019–2021. These vehicles utilize a variable-displacement engine oil pump containing an internal thermoplastic adjusting component responsible for regulating oil pressure. Field failures are increasingly being reported in which this internal component fractures, resulting in sudden loss or instability of engine oil pressure. The failure frequently occurs during cold-start operation in low ambient temperatures. When the component fails, oil pressure regulation becomes erratic or is lost entirely. In many cases, drivers receive little or no actionable warning prior to engine damage or vehicle disablement. Reported precursor symptoms include inability to electronically measure engine oil level, abnormal oil pressure behavior, or sudden drivetrain malfunction warnings. Failures may rapidly progress to engine shutdown or severe mechanical damage caused by oil starvation. Loss of lubrication can cause the vehicle to become disabled without warning while driving or shortly after startup. This creates a safety hazard, particularly when vehicles become immobilized in active traffic or during winter conditions the cold is when they fail the most, where occupants may be exposed to freezing temperatures while awaiting assistance. Replacement of the oil pump requires extensive disassembly of the vehicle and repairs commonly exceed $6,000–$8,000 for just the pump, assuming the motor is unharmed. Failures have been reported across multiple production years, and affected vehicle population boundaries remain unclear. Because this condition can result in sudden vehicle disablement without adequate warning especially in the cold, I believe this issue warrants investigation as a potential safety-related defect.

NHTSA ID

11740705

Incident

May 25, 2026

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. A luxury vehicle should not have this many significant failures in such a short span of ownership. Between the repair costs, downtime, and constant concern over what will fail next, this car has completely destroyed my confidence in the BMW brand. I am documenting these issues formally because this ownership experience has been unacceptable.

NHTSA ID

11738468

Incident

May 18, 2026

I am reporting a safety concern with BMW vehicles equipped with the B58 Technical Update (B58TU) engine, primarily in 2019–2021 model years. These vehicles use a variable-displacement oil pump containing an internal thermoplastic adjusting component that regulates oil pressure. This plastic part is prone to fracturing, leading to sudden loss or instability of engine oil pressure. Failures most commonly occur during cold starts in low ambient temperatures. When the component breaks, oil pressure regulation fails with little or no warning. Drivers often experience precursor symptoms such as inability to electronically read oil level, erratic oil pressure, or sudden drivetrain warnings. The issue can rapidly progress to engine shutdown or severe damage from oil starvation. This creates a serious safety hazard, as the vehicle can become disabled without warning while driving or shortly after startup — particularly dangerous in traffic or winter conditions when failures are most frequent, potentially stranding occupants in freezing temperatures. Oil pump replacement requires extensive disassembly and typically costs $6,000–$8,000 for the pump alone, assuming no further engine damage. Owners cannot reliably determine if their vehicle still has the original thermoplastic pump. VIN-based parts lookups now display the updated metal-component part number even when no replacement has occurred. BMW has also removed the original plastic part number from dealer systems, eliminating transparency. This issue affects multiple production years and continues to impact vehicles in the field

NHTSA ID

11738024

Incident

Mar 12, 2026

I am reporting a safety concern involving BMW vehicles equipped with the B58 Technical Update (B58TU) engine, commonly found in model years 2019–2021. These vehicles utilize a variable-displacement engine oil pump containing an internal thermoplastic adjusting component responsible for regulating oil pressure. Field failures are increasingly being reported in which this internal component fractures, resulting in sudden loss or instability of engine oil pressure. The failure frequently occurs during cold-start operation in low ambient temperatures. When the component fails, oil pressure regulation becomes erratic or is lost entirely. In many cases, drivers receive little or no actionable warning prior to engine damage or vehicle disablement. Reported precursor symptoms include inability to electronically measure engine oil level, abnormal oil pressure behavior, or sudden drivetrain malfunction warnings. Failures may rapidly progress to engine shutdown or severe mechanical damage caused by oil starvation. Loss of lubrication can cause the vehicle to become disabled without warning while driving or shortly after startup. This creates a safety hazard, particularly when vehicles become immobilized in active traffic or during winter conditions the cold is when they fail the most, where occupants may be exposed to freezing temperatures while awaiting assistance. As I waited for 4hr in -15c. Replacement of the oil pump requires extensive disassembly of the vehicle and repairs costed $8349 for just the pump, assuming the motor is unharmed. Owners are currently unable to determine whether their vehicles contain the original thermoplastic oil pump design or a later revised version utilizing metal internal components, as VIN-based parts information now identifies updated components in the car even when no replacement has occurred and the old components are actually in the car. Also, BMW has actively removed the plastic part number out of all dealer networks as well.

NHTSA ID

11724191

Incident

Jan 22, 2026

Started as low creaking noise coming from front left wheel. Slow speeds, over small bumps. Over time (one month), creaking noises became louder and more frequent. At that time, steering was starting to feel stiff when turning to the left. Taken to 2 BMW dealerships who said it was just a noise and that both tie rods would have to be replaced. Upon further investigation, these noises and handling are a result of the torque being too tight at the factory upon manufacturer.

NHTSA ID

11692586

Incident

Oct 8, 2025

While driving through an intersection and making a left turn, a failure of the engine water pump pulley caused the pulley to break apart. This led to damage to the coolant line and tensioner, sudden coolant loss, and the serpentine belt slipping off. The failure occurred mid-turn, causing the vehicle to skid and momentarily lose steering control. I narrowly avoided a collision with an oncoming vehicle that was stopped at a red light. The vehicle was towed to an independent repair shop, where mechanics confirmed that the water pump pulley had failed and caused the resulting damage. The vehicle is just over 4 years old and has approximately 58,000 miles. This type of failure—especially in a well-maintained vehicle with all scheduled maintenance completed on time—is unexpected and presents a serious safety concern.

NHTSA ID

11656393

Incident

Apr 22, 2025

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).

NHTSA ID

11553344

Incident

Oct 1, 2023

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).

NHTSA ID

11553343

Incident

Oct 2, 2023

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.

NHTSA ID

11491782

Incident

Mar 1, 2021

Mileage

4,000 mi