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BMW · Known Issues

2021 BMW 4 Series Problems: 1 Known Issue

2021 model year · 250+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 250+ owner reports, the 2021 BMW 4 Series has 1 documented issue. None of the listed issues is rated critical; this is not a complete reliability assessment. The most commonly reported issue is B58 Charge Pipe Pop-Off Under Boost with 250 owner reports. Across all issues with published estimates, repair costs range from $200 to $500. DIY maintenance guides at au7o.io.

In This Article

  • 4 Series Engine1
  • Recalls1
  • FAQ
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In This Article

  • Engine1
  • Recalls1
  • FAQ

All 1 Known Issue

Filter:
ALL YEARS202520242023202220212020201920182017201620152014
Community reported
250 owners

On the 2017-2025 BMW 4 Series B58, the plastic charge pipe (intercooler to throttle body) on B58-powered 440i and M440i models can pop off or crack under high boost pressure, especially in warm weather or during spirited driving. The OEM plastic pipe uses a pressed-on connector that weakens over heat cycles. When the pipe disconnects, the engine immediately loses boost pressure and enters limp mode with significant power loss.

This issue also affects: BMW 2 Series, BMW 5 Series, BMW M5

Common Symptoms

  • Sudden loss of power during hard acceleration
  • Loud pop or hissing sound from engine bay
  • Boost pressure fault codes stored in DME
  • Check Engine light with underboost code
  • Engine running rough after the pipe disconnects
  • Whistling or whooshing noise under throttle

How to Fix

Replace the OEM plastic charge pipe with an upgraded aluminum aftermarket unit. These use proper clamp-style connections that won't pop off under pressure. If replacing with OEM, use the latest revision part number. Check the intercooler boots and couplings for damage from the pressure release event.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • BMS Elite Gen1 B58 F-chassis aluminum charge pipe

    Select the correct engine option and confirm chassis before ordering..

    Burger Tuning
  • BMS B58TU Gen2 G-chassis charge pipe

    The vendor page does not currently confirm 2025, so do not extend this link to 2025 without revalidation..

    Burger Tuning

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$200 - $500

Research This Issue

Based on 250 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerified250 owner reportsLast reported by owners Mar 2026Reviewed Aug 2026
NHTSA Recalls1 recall

POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)

BMW of North America, LLC (BMW) is recalling certain 2023 Toyota GR Supra, 3 Series Sedan (330i xDrive, M340i xDrive, M3), 5 Series Sedan (530i, 530i xDrive, M5), 4 Series Gran Coupe (430i, 430i xDrive), 4 Series Coupe (430i, 430i xDrive, M440i xDrive), 4 Series Convertible (430i, 430i xDrive, M440i xDrive), 8 Series Coupe (840i, M850i xDrive, M8), 8 Series Convertible (840i, M850i xDrive, M8), 8 Series Gran Coupe (850i xDrive, M8), X3 SAV (X3 xDrive30i, X3M), X4 SAV (X4 xDrive30i), X5 SAV (X5 xDrive40i, X5 M50i, X5M), X6 SAV (X6 xDrive40i, X6 M50i, X6M), and Z4 sDrive30i, Z4 M40i vehicles. The weld seam of the integrated transmission control unit's cover may not have been manufactured properly, which could allow automatic transmission oil to leak into the transmission control unit.

Campaign #23V82100006/12/2023

Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.

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Other BMW Models

BMW M332BMW 3 Series27BMW i525BMW M522BMW M340i22BMW 6 Series21

Frequently Asked Questions

What are the most common BMW 4 Series problems?

According to Au7o's analysis of 250+ owner reports, the 2021 BMW 4 Series has 1 documented issue. The documented issue is: B58 Charge Pipe Pop-Off Under Boost. None are rated critical, but regular maintenance is recommended.

Is the BMW 4 Series reliable?

The 2021 BMW 4 Series has 1 known issue documented across 250+ owner reports. None of the matching records is rated critical; this is not a complete reliability assessment. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common BMW 4 Series problems?

Repair costs for known BMW 4 Series issues range from $200 to $500, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2017-2025 BMW 4 Series B58 Charge Pipe Pop-Off Under Boost?

The plastic charge pipe (intercooler to throttle body) on B58-powered 440i and M440i models can pop off or crack under high boost pressure, especially in warm weather or during spirited driving. The OEM plastic pipe uses a pressed-on connector that weakens over heat cycles. When… Repairs typically run $200-$500. Severity: medium.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data sourced from 250+ owner reports, NHTSA recalls, TSBs, and automotive forums.