2024 BMW M340i Problems: 5 Issues Every Owner Should Know

2024 model year · 1,250+ owner reports · Updated April 2026

According to Au7o's analysis of 1,250+ owner reports, the 2024 BMW M340i has 5 documented known issues, with 2 rated critical. The most serious are Coolant Loss from Expansion Tank and Water Pump ($400-$1,200 repair) and High-Pressure Fuel Pump (HPFP) Failure ($600-$1,500 repair). The most commonly reported issue is Coolant Loss from Expansion Tank and Water Pump with 380 owner reports. Across all issues, repair costs range from $50 to $2,000. DIY maintenance guides at au7o.io.

All 5 Known Issues

Filter:

When Issues Typically Appear

Oil Filter Disintegration in Housing

5K-7K

Coolant Loss from Expansion Tank and Water Pump

18K-60K

Intake Valve Carbon Buildup

50K-80K

025K50K75K100K mi

Community Reported

380 owners

On the 2020-2024 BMW M340i B58 3.0L Turbo I6, the M340i's B58 engine experiences the same coolant loss issues as other B58-powered BMWs, but the M340i's higher sustained performance driving tends to accelerate the problem. The plastic coolant expansion tank develops hairline cracks from heat cycling, and the electric water pump can fail prematurely. BMW issued a TSB for the coolant vent line on the cylinder head that deteriorates under high temperatures. Many M340i owners report needing to top off coolant more frequently than expected, even on low-mileage vehicles.

This issue also affects: Audi A4 allroad, BMW M240i, BMW X3

Common Symptoms

Coolant level dropping between services
Low coolant warning on iDrive
Sweet antifreeze smell from engine compartment
Visible coolant residue or white deposits around expansion tank
Engine temperature gauge reading higher than normal
Steam from engine bay in severe cases

How to Fix

Replace the coolant expansion tank at first sign of cracking. Proactively replace the electric water pump before 60,000 miles. Replace the coolant vent line per BMW TSB. Use only BMW-approved blue coolant. Monitor coolant level monthly and pressure test the cooling system at every major service.

What Owners Are Using

Parts and tips from 380+ owners who fixed this issue

NoteThe B58 can go from 'low coolant' to 'overheated' very quickly. If you see the warning, pull over immediately. Driving even 5 minutes with overheating can warp the aluminum head.
UpgradeFCP Euro carries the OEM Mahle water pump with their lifetime replacement guarantee. Worth every penny for this known failure item.
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Typical repair cost:$400 - $1,200

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380+ owners have reported this issue

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Community Reported

High Confidence380 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

195 owners

On the 2020-2024 BMW M340i B58 3.0L Turbo I6, the B58 engine's high-pressure fuel pump can fail, though at lower rates than the older N54 engine. When the HPFP fails, fuel pressure drops below the minimum required for proper direct injection, causing long cranking, rough idle, misfires, and in severe cases, the engine stalling and entering limp mode. Failures are more common in cold weather when fuel demands are higher, and can be exacerbated by ethanol-blended fuels.

This issue also affects: Chevrolet Silverado 2500HD, Jeep Grand Wagoneer, Lexus IS

Common Symptoms

Long cranking before engine starts, especially in cold weather
Engine stalling at idle or low speed
Check engine light with fuel pressure codes
Noticeable loss of power during acceleration
Rough idle and misfires

How to Fix

Replace the high-pressure fuel pump with the latest revised BMW part number. Verify the low-pressure fuel pump is providing adequate feed pressure. Use top-tier fuel and avoid running the tank below 1/4 to reduce strain on the fuel system. If under warranty, BMW will cover HPFP replacement.

What Owners Are Using

Parts and tips from 195+ owners who fixed this issue

TipLog fuel pressure data with an OBD scanner like the BimmerLink app. Fuel pressure below 150 bar at full load is a sign the HPFP is failing before you get a check engine light.
TipThe B58 HPFP is significantly more reliable than the N54's notorious pump. Most B58 HPFP failures occur on tuned cars - stock cars rarely have this issue before 80k miles.
UpgradeDelphi fuel pump module — OE-quality direct replacement (Delphi Fuel Pump Module)
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UpgradeBosch fuel pump — reliable OEM alternative (Bosch Fuel Pump)
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Typical repair cost:$600 - $1,500

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195+ owners have reported this issue

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Community Reported

Medium Confidence195 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

290 owners

On the 2020-2024 BMW M340i B58 3.0L Turbo I6, as a direct-injection engine, the B58 in the M340i does not have fuel washing over the intake valves, leading to gradual carbon deposit buildup on the valve backs. Oil vapors from the crankcase ventilation system deposit carbon that restricts airflow and reduces performance. Symptoms typically become noticeable after 50,000-80,000 miles, with rough idle, reduced throttle response, and minor misfires. The M340i's higher boost pressures can accelerate carbon accumulation compared to non-M B58 applications.

This issue also affects: Citroën C3, Hyundai Santa Fe, Hyundai Tucson

Common Symptoms

Rough or uneven idle developing gradually
Reduced throttle response and power
Slight hesitation during acceleration from low RPM
Minor misfires at idle, especially when cold
Decreased fuel economy over time

How to Fix

Walnut blast the intake valves every 50,000-60,000 miles. This involves removing the intake manifold and blasting walnut shell media at the valve backs to remove carbon deposits. Some owners use catch cans to reduce oil vapor entering the intake. BMW's official position is that carbon buildup is normal for direct-injection engines.

What Owners Are Using

Parts and tips from 290+ owners who fixed this issue

TipSchedule a walnut blast at 50k miles as preventive maintenance. It costs $400-600 at an independent BMW shop and makes a huge difference in how the engine runs.
TipAn oil catch can from Burger Motorsports or Mishimoto can significantly reduce carbon buildup by catching oil vapors before they enter the intake. Not a complete solution but helps extend time between walnut blasts.
UpgradeIntake manifold gasket set seals coolant and vacuum leaks (Fel-Pro Intake Manifold Gasket Set)
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UpgradeReplacement intake manifold for cracked or warped originals (Dorman Intake Manifold)
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Typical repair cost:$400 - $800

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290+ owners have reported this issue

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Community Reported

High Confidence290 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

165 owners

On the 2020-2024 BMW M340i, the B58 engine has a documented tendency for paper oil filters to shred and break apart during normal use. As oil passes through the filter under pressure, the filter media can separate from the end caps and tear into multiple pieces. Shredded filter material can deposit paper fragments in the oil filter housing and potentially circulate through the oil system. This is more common with non-OEM filters but has been reported with genuine BMW filters as well.

This issue also affects: BMW 5 Series, BMW M240i, BMW Z4

Common Symptoms

Oil filter found shredded or torn during oil change
Paper debris visible in oil filter housing
Low oil pressure warning (if fragments restrict flow)
Oil appearing darker than expected between changes
Fine metal particles in oil (if unfiltered oil reaches bearings)

How to Fix

Use only genuine BMW or Mann-branded oil filters (Mann is the OEM supplier). Change oil and filter every 5,000-7,000 miles rather than BMW's recommended 10,000-mile interval. When removing the old filter, inspect it carefully for signs of deterioration. If filter fragments are found in the housing, flush the housing thoroughly before installing the new filter.

What Owners Are Using

Parts and tips from 165+ owners who fixed this issue

NoteNever use cheap aftermarket oil filters on the B58. The OEM Mann filter is only $8-12 and specifically engineered for the pressure and flow characteristics of this engine.
TipShorten your oil change interval to 5,000-7,000 miles regardless of what BMW's oil life monitor says. The 10,000-mile interval is too long for the B58, especially in performance driving.
UpgradeBluetooth OBD-II scanner for reading engine codes and monitoring live data (BlueDriver Bluetooth OBD2 Diagnostic Scan Tool)
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UpgradeQuality synthetic oil and filter combo for engine maintenance (Mobil 1 Full Synthetic Oil and Filter Bundle)
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Typical repair cost:$50 - $200

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165+ owners have reported this issue

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Community Reported

Medium Confidence165 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

220 owners

On the 2020-2024 BMW M340i B58 3.0L Turbo I6, the B58 engine's electronic wastegate actuator can develop play over time, producing a characteristic rattling or buzzing noise at idle and during deceleration. The wastegate flapper valve develops clearance within its housing, causing it to vibrate at certain RPMs. While often described as just an annoyance, a severely worn wastegate can lead to boost control issues, over-boost or under-boost conditions, and eventually check engine lights for boost deviation faults.

This issue also affects: Audi A3, Audi A6, Audi Q5

Common Symptoms

Rattling or buzzing noise at idle from turbocharger area
Metallic vibration sound during deceleration
Check engine light with boost control codes (advanced cases)
Intermittent boost fluctuations at steady throttle
Noise more pronounced in cold weather

How to Fix

Have the wastegate actuator inspected for excessive play. Minor rattle without fault codes can be monitored. If boost control faults develop, replace the turbocharger wastegate actuator. In severe cases, the entire turbocharger assembly may need replacement. BMW may cover under warranty if fault codes are present.

What Owners Are Using

Parts and tips from 220+ owners who fixed this issue

TipA minor wastegate rattle without any codes is cosmetic - many B58 owners live with it for years without issues. Only worry if you get boost-related fault codes.
UpgradeTurbo gasket kit prevents boost leaks and oil seepage at the turbo flanges (Dorman Turbocharger Gasket Kit)
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UpgradeBoost gauge helps monitor turbo performance and catch problems early (AutoMeter Mechanical Boost Gauge)
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Typical repair cost:$200 - $2,000

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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

Frequently Asked Questions

What are the most common BMW M340i problems?

According to Au7o's analysis of 1,250+ owner reports, the 2024-2024 BMW M340i has 5 documented issues. The most frequently reported are: Coolant Loss from Expansion Tank and Water Pump, High-Pressure Fuel Pump (HPFP) Failure, Intake Valve Carbon Buildup. Of these, 2 are rated critical and should be addressed promptly.

Is the BMW M340i reliable?

The 2024-2024 BMW M340i has 5 known issues documented across 1,250+ owner reports. 2 issues are rated critical: Coolant Loss from Expansion Tank and Water Pump and High-Pressure Fuel Pump (HPFP) 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 M340i problems?

Repair costs for known BMW M340i issues range from $50 to $2,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Coolant Loss from Expansion Tank and Water Pump, typically costs $400-$1,200 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2020-2024 BMW M340i Coolant Loss from Expansion Tank and Water Pump?

The M340i's B58 engine experiences the same coolant loss issues as other B58-powered BMWs, but the M340i's higher sustained performance driving tends to accelerate the problem. The plastic coolant expansion tank develops hairline cracks from heat cycling, and the electric water p… Repairs typically run $400-$1,200. Severity: high.

What is the 2020-2024 BMW M340i High-Pressure Fuel Pump (HPFP) Failure?

The B58 engine's high-pressure fuel pump can fail, though at lower rates than the older N54 engine. When the HPFP fails, fuel pressure drops below the minimum required for proper direct injection, causing long cranking, rough idle, misfires, and in severe cases, the engine stalli… Repairs typically run $600-$1,500. Severity: high.

What is the 2020-2024 BMW M340i Intake Valve Carbon Buildup?

As a direct-injection engine, the B58 in the M340i does not have fuel washing over the intake valves, leading to gradual carbon deposit buildup on the valve backs. Oil vapors from the crankcase ventilation system deposit carbon that restricts airflow and reduces performance. Symp… Repairs typically run $400-$800. Severity: medium.

What is the 2020-2024 BMW M340i Oil Filter Disintegration in Housing?

The B58 engine has a documented tendency for paper oil filters to shred and break apart during normal use. As oil passes through the filter under pressure, the filter media can separate from the end caps and tear into multiple pieces. Shredded filter material can deposit paper fr… Repairs typically run $50-$200. Severity: medium.

What is the 2020-2024 BMW M340i Turbo Wastegate Rattle at Idle?

The B58 engine's electronic wastegate actuator can develop play over time, producing a characteristic rattling or buzzing noise at idle and during deceleration. The wastegate flapper valve develops clearance within its housing, causing it to vibrate at certain RPMs. While often d… Repairs typically run $200-$2,000. Severity: low.

2024 BMW M340i Problems: 5 Issues Every Owner Should Know

All 5 Known Issues

When Issues Typically Appear

2020-2024 BMW M340i: Coolant Loss from Expansion Tank and Water Pump#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2020-2024 BMW M340i: High-Pressure Fuel Pump (HPFP) Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2020-2024 BMW M340i: Intake Valve Carbon Buildup#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2020-2024 BMW M340i: Oil Filter Disintegration in Housing#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2020-2024 BMW M340i: Turbo Wastegate Rattle at Idle#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other BMW Models

Frequently Asked Questions

What are the most common BMW M340i problems?

Is the BMW M340i reliable?

How much does it cost to fix common BMW M340i problems?

What is the 2020-2024 BMW M340i Coolant Loss from Expansion Tank and Water Pump?

What is the 2020-2024 BMW M340i High-Pressure Fuel Pump (HPFP) Failure?

What is the 2020-2024 BMW M340i Intake Valve Carbon Buildup?

What is the 2020-2024 BMW M340i Oil Filter Disintegration in Housing?

What is the 2020-2024 BMW M340i Turbo Wastegate Rattle at Idle?