Why is my BMW 330i leaking coolant at the oil filter housing?
Likely causes, ranked
- Cracked plastic oil filter housingShop
- OFH gaskets and oil cooler sealsShop
- Nearby plastic coolant flangesShop
Real-owner fix counts will appear here as reports come in.
DIY or shop: See DIY or shop section
Parts to check
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Short answer: G20 330i B48 engines often leak coolant from the plastic oil filter housing. Fix it early and consider aluminum so you are not paying the labor twice.
Symptom: Coolant dropping, sweet smell, residue on the OFH, or a low-coolant warning.
What to check first
- Check coolant weekly.
- Inspect the OFH for residue.
- Do not ignore a low-coolant warning.
- Ask about aluminum housing while labor is open.
Likely causes
- Cracked plastic oil filter housing. G20 330i B48 engines use a plastic OFH that can crack and leak coolant, sometimes before 60k miles. Many owners upgrade to aluminum.
- OFH gaskets and oil cooler seals. Seals can seep even when the housing looks intact. Replace the seal kit with the housing.
- Nearby plastic coolant flanges. Shops often replace brittle coolant connectors while the intake is off.
What it usually costs
Labor dominates. Aluminum parts cost more upfront and can avoid a repeat.
Is it safe to keep driving?
Do not drive with a low coolant warning.
DIY or shop?
Experienced DIY possible; most use an indie BMW shop.
Recalls, bulletins and complaints in plain words
- Related recalls: NHTSA lists these recalls touching this area of the BMW 330i: 19V732000 (2019-2020 model years, engine); 25V636000 (2019-2021 model years, electrical system:starter assembly:relay); 26V056000 (2021-2024 model years, electrical system:starter assembly). Check your VIN at nhtsa.gov/recalls. If your car is part of this recall, the dealer fixes it for free.
- Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
- NHTSA complaints: 11 keyword-matched complaints for BMW 330i 2019–2024 (of 135 unique complaints queried, NHTSA complaints API by model year, queried 2026-11-07; keywords: oil filter, housing, coolant, leak) (NHTSA returned no data for 2 model-year queries). This counts complaints that mention these words. It is not a defect finding.
What owners report
- In Just lost an 8 year old car due to coolant leak/oil filter housing (B48) on Reddit r/BMW, an owner lost a car after an OFH-related coolant failure.
- In Oil Filter Housing B48 on Reddit r/BmwTech, owners discussed B48 OFH leaks.
- In Is the B48 engine reliable? on Reddit r/BMW, owners flagged the plastic OFH as a known weak point.
- In In the market for a 330i or 330e (G20) on Reddit r/BMW, buyers were warned to watch the oil filter housing.
Quick tip
330i losing coolant near the OFH? Fix it before a trip and strongly consider aluminum.
Vehicle focus: BMW 330i G20 with B48 roughly 2019-2024.
Safety / mechanic note
Coolant loss can cause sudden overheat. Verify with a mechanic.
Recalls & service bulletins
No recalls or service bulletins are listed for this page yet.
NHTSA complaints: 11 keyword-matched complaints for BMW 330i 2019–2024 (of 135 unique complaints queried, NHTSA complaints API by model year, queried 2026-11-07; keywords: oil filter, housing, coolant, leak) (NHTSA returned no data for 2 model-year queries).
Always check your VIN for open recalls at nhtsa.gov/recalls.
Sources
What actually fixed it?
Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.