IsItAGoodCar

Common Problems with the
2020–2021 BMW 3 Series (G20)

We've identified 5 known issues that can affect the 2020–2021 BMW 3 Series (G20). 2 of these are serious faults that could be expensive to repair.

5
Known Issues
2
Serious
2
Moderate
1
Minor

The 2020–2021 period has 4 more issues than the BMW 3 Series (G20) average across all year periods.

All Known Issues

Starter Motor Fire Risk (Recall)

SeriousElectrics & Electronics

A significant UK recall affects cars built between 2020 and 2022 where a faulty starter motor switch can overheat.

Most affected: Wide range of petrol and diesel models

Estimated cost: £0 (Recall)Affects: 2020–2022Often appears around: N/A

Typical symptoms

  • •Burning smell from the engine bay
  • •Car failing to start
  • •Warning message on dash

What to inspect before you buy

  • ✓Enter the VIN on the UK Government recall site to check status
  • ✓Ensure there is dealer documentation of the fix

Integrated Braking System (IBS) Recall

SeriousBrakes

A fault in the hydraulic braking assistance unit can lead to a loss of power assistance, requiring much higher pedal force to stop.

Most affected: Most models including M340i and 330e

Estimated cost: £0 (Recall)Affects: 2019–2024Often appears around: Any mileage

Typical symptoms

  • •Brake warning light on dash
  • •Significantly increased brake pedal effort required
  • •ABS/DSC system failures

What to inspect before you buy

  • ✓Verify recall status immediately
  • ✓If the pedal feels unusually hard, do not drive the car

Coolant Loss (B48 & B47 Engines)

ModerateCooling System

The plastic oil filter housing and coolant expansion tanks are known to crack or seep, leading to slow coolant loss that can go unnoticed until a warning appears.

Most affected: 318i, 320i, 330i, 318d, 320d

Estimated cost: £150–£600Affects: 2019–2024Often appears around: 30,000–60,000 miles

Typical symptoms

  • •Intermittent low coolant warning
  • •Sweet smell from the engine bay after a drive
  • •Dried pink/white residue around the expansion tank or oil filter area

What to inspect before you buy

  • ✓Inspect the oil filter housing for signs of weeping
  • ✓Check the expansion tank seam for hairline cracks
  • ✓Look for crusty residue on the undertray

Rear Differential Weeping

ModerateGearbox & Transmission

Early G20 models often suffer from a weeping rear differential seal, which can lead to oil loss and eventual diff failure if not addressed.

Most affected: 320d, 330i, 330d

Estimated cost: £300–£500Affects: 2019–2021Often appears around: 20,000–50,000 miles

Typical symptoms

  • •Oil spots on the driveway under the rear axle
  • •Dark, oily residue on the differential casing

What to inspect before you buy

  • ✓Inspect the rear differential from underneath during a pre-purchase inspection
  • ✓Look for any whining noises from the rear at motorway speeds

Infotainment (iDrive 7) Glitches

MinorElectrics & Electronics

iDrive 7 can suffer from random reboots, black screens, or GPS location errors. Most are software-related but some telematics modules fail.

Most affected: All models with iDrive 7

Estimated cost: £0–£300Affects: 2019–2021Often appears around: Any mileage

Typical symptoms

  • •Central screen going blank and restarting
  • •Apple CarPlay/Android Auto dropping out
  • •GPS showing the car in the wrong location

What to inspect before you buy

  • ✓Check if the "Remote Software Upgrade" feature is functional
  • ✓Test the physical iDrive controller for sticking buttons
  • ✓Verify phone connectivity stability

Buying Tips for the 2020 BMW 3 Series (G20)

  • ✓Verify that the starter motor fire risk and IBS (Integrated Braking System) recalls have been completed
  • ✓Check for inner shoulder wear on the rear tyres, as the G20 can be sensitive to rear alignment
  • ✓Listen for wind noise around the A-pillars at motorway speeds, which may require acoustic glass or seal adjustment
  • ✓On 330e PHEV models, verify the charging port door operates smoothly and the electric range is as expected
2019 BMW 3 Series (G20)2022 BMW 3 Series (G20)

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Other BMW 3 Series (G20) Year Periods

20192020–202120222023–2024

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