2021 BMW M340i xDrive

The 2021 BMW M340i xDrive is a popular performance sedan known for its blend of luxury and sportiness. It’s powered by a potent 3.0-liter turbocharged inline-six engine (B58) producing 382 horsepower and 369 lb-ft of torque. The engine is paired exclusively with an 8-speed automatic transmission (ZF 8HP51). While appreciated for its engaging driving dynamics and comfortable interior, some owners have reported certain issues. Common praises include the engine’s responsiveness and smooth power delivery, the well-balanced handling, and the luxurious interior. Criticisms often revolve around the run-flat tires’ harsh ride quality, the cost of maintenance, and some minor electronic glitches.

Engine

B58 3.0L Turbocharged Inline-Six

• Rough Idle/Cold Start Issues
  • Description/Symptoms: Some owners have reported rough idling, particularly during cold starts. This can manifest as vibrations, hesitation, or an uneven engine sound.
  • Solution: In some cases, software updates have resolved the issue. In other cases, it has been the injectors.
  • Estimated Cost to Fix: Varies depending on the cause; software update is typically free. Injector replacement can range from $200-$400+ per injector plus labor.
  • Recalls: None Found
• Coolant Leaks
  • Description/Symptoms: Coolant leaks around the water pump and thermostat housing. This can cause the low coolant light to illuminate.
  • Solution: Replacement of the water pump, thermostat housing, or hoses.
  • Estimated Cost to Fix: $500 - $1200+
  • Recalls: None Found

Transmission

ZF 8HP51 8-Speed Automatic

• Harsh Shifting/Hesitation
  • Description/Symptoms: Some owners have experienced occasional harsh shifting, particularly at lower speeds, and/or hesitation when accelerating.
  • Solution: A software update to the transmission control module (TCM) can often resolve the issue. In some cases, a mechatronic unit replacement is required.
  • Estimated Cost to Fix: Software update typically covered under warranty. Mechatronic unit replacement: $2,000 - $4,000+
  • Recalls: None Found

Suspension

• Premature Suspension Component Wear
  • Description/Symptoms: Some owners have reported premature wear of suspension components, such as control arm bushings and dampers, leading to clunking noises or diminished handling.
  • Solution: Replacement of worn components.
  • Estimated Cost to Fix: $300 - $1000+ per component, depending on location and complexity.
  • Recalls: None Found

Electrical

• Infotainment System Glitches
  • Description/Symptoms: Intermittent glitches with the iDrive infotainment system, including freezing, lagging, or unexpected reboots.
  • Solution: Software updates are the first step. Hardware replacement (e.g., head unit) might be necessary in more severe cases.
  • Estimated Cost to Fix: Software updates typically free. Head unit replacement: $800 - $2,000+
  • Recalls: None Found
• Sensor Malfunctions
  • Description/Symptoms: Malfunctions in various sensors, such as those related to the parking assist system, adaptive cruise control, or tire pressure monitoring system (TPMS).
  • Solution: Diagnosis and replacement of the faulty sensor.
  • Estimated Cost to Fix: $100 - $500+ per sensor, depending on the type and location.
  • Recalls: None Found

Exterior

• No Issues Found

Interior

• Rattling/Buzzing Noises
  • Description/Symptoms: Some owners have reported rattling or buzzing noises emanating from the dashboard, door panels, or rear deck.
  • Solution: Identification and insulation of the source of the noise.
  • Estimated Cost to Fix: Varies greatly depending on the source and complexity. $100 - $500+
  • Recalls: None Found

Summary

The 2021 BMW M340i xDrive is a generally reliable vehicle, but some owners have reported issues ranging from minor glitches to more significant mechanical problems. Engine and transmission issues, while not widespread, can be costly to repair. Electrical gremlins with the infotainment system are also a relatively common complaint. While the severity varies, it’s prudent for prospective buyers to be aware of these potential issues and to thoroughly inspect the vehicle before purchase.