What are the most common BMW Z4 problems?

According to Au7o's analysis of 400+ owner reports, the 2026-2026 BMW Z4 has 2 documented issues. The most frequently reported are: B58 Coolant Expansion Tank Cracking, Electric Power Steering Rack Failure. Of these, 2 are rated critical and should be addressed promptly.

Is the BMW Z4 reliable?

The 2026-2026 BMW Z4 has 2 known issues documented across 400+ owner reports. 2 issues are rated critical: B58 Coolant Expansion Tank Cracking and Electric Power Steering Rack Failure. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common BMW Z4 problems?

Repair costs for known BMW Z4 issues range from $150 to $3,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, B58 Coolant Expansion Tank Cracking, typically costs $150-$600 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

2026 BMW Z4 Problems: 2 Issues Every Owner Should Know

2026 BMW Z4 Problems: 2 Issues Every Owner Should Know | Au7o

All 2 Known Issues

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Community Reported

220 owners

On the 2019-2026 BMW Z4 B58, the G29 Z4 with the B58 3.0L turbo inline-6 shares the common BMW plastic coolant expansion tank weakness. The tank develops hairline cracks from heat cycling and pressure, causing slow coolant leaks that can progress to sudden tank failure and overheating. The issue is exacerbated by the Z4's tighter engine bay packaging which increases under-hood temperatures.

This issue also affects: BMW 5 Series, BMW 3 Series, BMW 4 Series

Common Symptoms

Low coolant warning
Coolant smell
Visible cracks on expansion tank
Coolant puddle under car
Overheating warning
White residue around tank cap
Steam from engine bay

How to Fix

Replace the coolant expansion tank with an updated BMW part or aftermarket aluminum tank. Inspect the tank and cap regularly for signs of cracking, discoloration, or seepage. When replacing, also replace the cap and check all coolant hoses for brittleness. Flush and refill with BMW-approved coolant.

What Owners Are Using

Parts and tips from 220+ owners who fixed this issue

UpgradeAluminum coolant expansion tank upgrade — eliminates the cracking issue permanently (Mishimoto #MMRT-B58-20)
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TipCheck the expansion tank at every oil change — catching a crack early prevents an overheating event.
NoteDo NOT open the expansion tank cap when the engine is hot — the pressurized coolant will spray and cause burns.

Typical repair cost:$150 - $600

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220+ owners have reported this issue

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Community Reported

High Confidence220 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

180 owners

On the 2009-2026 BMW Z4, both E89 and G29 Z4 models can experience electric power steering (EPS) rack failure. The EPS motor or its control unit can fail, causing heavy steering, intermittent loss of power assist, or steering fault warnings. The E89 is more commonly affected, but G29 models have also reported issues. The compact Z4 chassis amplifies the heavy steering feeling when assist is lost.

Common Symptoms

Heavy steering
Steering assist fault warning
Intermittent loss of power assist
Steering pulls to one side
Clunking when turning at low speed
Check engine light with steering codes
Steering feels different left vs right

How to Fix

Diagnose whether the fault is in the EPS motor, control unit, or wiring. In many cases, the entire steering rack assembly must be replaced as the EPS motor is integrated. After replacement, a steering angle sensor calibration is required. Some E89 racks can be rebuilt by specialists for less cost.

What Owners Are Using

Parts and tips from 180+ owners who fixed this issue

NoteLoss of power steering assist in a Z4 makes the car difficult to maneuver at low speeds — do not ignore early symptoms.
TipEPS rack rebuilders like Maval and DriveRite offer remanufactured units at 40-60% of new OEM cost.
TipCheck the EPS wiring connector under the steering column — corrosion or a loose connection can mimic a failed rack.
UpgradeInner and outer tie rod ends for steering precision restoration (Moog Tie Rod End)
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UpgradeRemanufactured power steering rack for complete steering system repair (Cardone Remanufactured Steering Rack)
View on Amazon

Typical repair cost:$800 - $3,500

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180+ owners have reported this issue

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Community Reported

Medium Confidence180 reportsLast reported by owners Mar 2026Reviewed Mar 2026

⚠️NHTSA Recalls4 recalls

VISIBILITY:POWER WINDOW DEVICES AND CONTROLS

BMW of North Americal, LLC (BMW) is recalling certain 2023 8 Series Coupe (840i, 840i xDrive, M850i xDrive, M8), 8 Series Convertible (840i, 840i xDrive, M850i xDrive, M8), 8 Series Gran Coupe (840i, 840i xDrive, M850i xDrive, M8, Alpine B8 xDrive), 2 Series Coupe (230i, 230i xDrive, M240i xDrive, M2), and 2022-2023 Z4 sDrive30i, Z4 M40i vehicles. When the digital key is removed from the vehicle, the Electronic Control Unit (ECU) software may still allow the power windows and sunroof to be closed. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 118, "Power-operated Window Systems."

Campaign #23V09900017/02/2023

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

ELECTRICAL SYSTEM:STARTER ASSEMBLY:RELAY

BMW of North America, LLC (BMW) is recalling certain 2019-2021 BMW 330i, 2019-2022 BMW Z4, 2020-2022 BMW 530i, X3, X4, Toyota Supra, 2021-2022 BMW 430i, 430i Convertible, and 2022 BMW 230i vehicles. The engine starter relay may corrode, causing the relay to overheat and short circuit.

Campaign #25V63600023/09/2025

ELECTRICAL SYSTEM:STARTER ASSEMBLY

BMW of North America, LLC (BMW) is recalling certain 2021-2023 Toyota Supra, 2022-2023 2 Series Coupe, 2021-2024 5 Series (xDrive), 2021-2022 Z4, 2022-2024 4 Series (Gran Coupe), 2021-2024 4 Series (Convertible and xDrive Convertible), 2021-2023 4 Series (Coupe), 2021-2024 3 Series, 2021-2023 X4, 2021-2024 X3 vehicles. Please see the recall report for a complete list of all models. The engine starter may overheat and catch fire due to wear on an internal component.

Campaign #26V05600030/01/2026

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

2026 BMW Z4 Problems: 2 Issues Every Owner Should Know

All 2 Known Issues

2019-2026 BMW Z4: B58 Coolant Expansion Tank Cracking#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2009-2026 BMW Z4: Electric Power Steering Rack Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other BMW Models

Frequently Asked Questions

What are the most common BMW Z4 problems?

Is the BMW Z4 reliable?

How much does it cost to fix common BMW Z4 problems?

What is the 2019-2026 BMW Z4 B58 Coolant Expansion Tank Cracking?

What is the 2009-2026 BMW Z4 Electric Power Steering Rack Failure?