2021 BMW M340i Problems

Complaints Reported

Complaints by Component

ENGINE

2 complaints

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).

Nov 03, 2023

STEERING,SUSPENSION

1 complaint

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.

Oct 10, 2025

POWER TRAIN

1 complaint

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.

Apr 23, 2025

POWER TRAIN,SERVICE BRAKES

1 complaint

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.

Nov 01, 2022

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4.6/5.0

57 reviews

Frequently Asked Questions

How many problems does the 2021 BMW M340i have?

The 2021 BMW M340i currently has 5 owner-reported complaints according to NHTSA database. These complaints are organized by component to help identify common issues.

What are the most common problems with 2021 BMW M340i?

The most common problems reported for the 2021 BMW M340i are organized by component above. Each component section shows owner-reported issues, crash reports, and fire incidents to help identify patterns and problem areas.

Where does this 2021 BMW M340i problem data come from?

All problem and complaint data for the 2021 BMW M340i comes directly from the National Highway Traffic Safety Administration (NHTSA) database. These are real complaints submitted by actual vehicle owners.