BMW N20 and N55 petrol engines (August 2011 to March 2012 builds): plastic oil filter housing oil or coolant leak

At a glance

Severity

Moderate a function degrades but the car still drives; planned repair.
Severity follows the worst documented outcome, not the average case.

Safety-relevant

Not flagged as safety-relevant.

In the Elgarde checklist

Ordinary entry: it does not cap the verdict by itself.

Documented in

US

Which cars this covers

BMW cars with the N20 engine (E84 X1, E89 Z4, F10 5 Series, F25 X3, F30 3 Series) or the N55 engine in the F30 3 Series built from August 2011 to March 2012, and other N55 cars of these series built from August 2011 to January 2012, and only if the oil filter housing is the black plastic type. Other BMW engines and other build dates are not covered.

Models in scope

BMW X1, BMW Z4, BMW 5 Series, BMW X3, BMW 3 Series

Conditions on top of the model

• At least one of these must hold:
  • All of these must hold:
    • Production date: August 2011 to March 2012
    • At least one of these must hold:
      • Engine: BMW N20 petrol
      • All of these must hold:
        • Engine: BMW N55 inline-six petrol
        • Model: BMW 3 Series
  • All of these must hold:
    • Engine: BMW N55 inline-six petrol
    • Production date: August 2011 to January 2012

Notes on scope

The BMW bulletins are US service documents (BMW of North America); whether the same housings were fitted to European-market cars is not stated in them. BMW's N55 service action names only the F30; a separate BMW information bulletin lists the black plastic housing on N20 and N55 engines in E84, E89, F10, F10H, F25 and F30 cars built from August 2011 to January 2012, so other N55 cars of those builds are included as possible: check the housing colour. The N20 action lists labour operations for inspection only (aluminium) and for replacement (plastic). No failure rate or repair cost is published in the sources used here.

How to check whether a particular car is affected

Elgarde reads the conditions above and gives one of three answers for a car:

• Applies: every condition is confirmed for the car.
• Possible: at least one condition cannot be confirmed yet. The entry stays on the checklist, with a note on what to find out.
• Not applicable: a condition is clearly not met (for example a manual gearbox on a DSG entry). The entry is left off the checklist.

What to look for, and where

• Model: one of the models listed above
  The model name as on the registration document, e.g. Golf, 208, 320d.
• Production month: August 2011 to March 2012
  The month the car was built (on the VIN plate or in the registration papers). It only matters when the year alone does not settle it.
• Engine code: BMW N20 petrol
  On the engine plate or block, or from a dealer VIN query. Displacement (P.1) and power in kW (P.2) on the registration certificate help narrow it down.

When in doubt, treat the car as possible: asking one question too many costs less than missing a defect.

How the fault arises, as reported

According to BMW's service actions, the plastic oil filter housing fitted to N20 and N55 engines in the stated builds may fail and lead to an internal and/or external leak of engine oil or coolant. BMW's remedy is to replace the plastic (black) housing with a new one; cars already fitted with the aluminium (silver) housing need no action. The BMW documents give no cause for the failure.

Reported symptoms

Early signs

• Engine oil or coolant leaking at the oil filter housing

Later signs

• Internal leak of engine oil or coolant

What to check when inspecting a car

• Documents and records. Confirm the engine (N20, or N55) and the build date (door-pillar label or dealer VIN query): August 2011 to March 2012 for the N20 and the N55 in an F30, August 2011 to January 2012 for other N55 cars.Red flag: Engine and build date in range.
• Visual check. Look at the oil filter housing: black plastic is the type BMW's service action replaces; silver aluminium needs no action. Look around it for oil or coolant residue.Red flag: Black plastic housing, or oil or coolant residue around it.
• Documents and records. Ask for invoices showing the oil filter housing was inspected or replaced under BMW's service action (SI B11 13 15 for N20, SI B11 14 15 for N55).Red flag: Plastic housing in the build window and no record of the action.

Repair and cost

Usual remedy

Replacement of the plastic oil filter housing (with the related seals and coolant hoses listed in the BMW bulletin) on cars that have the black plastic type; no action for the aluminium type.

No published repair cost is recorded in this dossier.

What the manufacturer and regulators have said

Manufacturer programme

BMW service actions SI B11 13 15 (N20) and SI B11 14 15 (N55), 2015: dealers inspect the housing and replace the plastic (black) type. The bulletins give dealer reimbursement labour operations but do not state the terms for owners. Sources: [1], [2]

Official records and rulings

• Technical service bulletin · BMW of North America (hosted by NHTSA) · SI B11 13 15 · 2015-08
  BMW service action: the plastic oil filter housing may fail and lead to an internal and/or external engine oil or coolant leak. Applies to E84, E89, F10, F25 and F30 with the N20 engine produced August 2011 to March 2012. Procedure: inspect; if the housing is aluminium (silver) take no action; if plastic (black), replace the housing. [1] static.nhtsa.gov
• Technical service bulletin · BMW of North America (hosted by NHTSA) · SI B11 14 15 · 2015-10
  BMW service action for the N55 engine with the same wording: the plastic oil filter housing may fail and lead to an internal and/or external engine oil or coolant leak. Applies to the F30 (3 Series sedan) produced August 2011 to March 2012; aluminium (silver) housing: no action; plastic (black) housing: replace. [2] static.nhtsa.gov
• Technical service bulletin · BMW of North America (hosted by NHTSA) · SI B11 05 15 · 2015-03
  BMW information bulletin: N20 and N55 engines in E84, E89, F10, F25 and F30 produced August 2011 to January 2012 were built with a black plastic oil filter housing; it lists the matching oil filter part numbers. Confirms that the plastic housing exists on both engines in those builds. [3] static.nhtsa.gov

A recall or campaign record describes the vehicles in its scope, not a confirmed failure in any given car.

How common is it?

Evidence and sources

Each statement above traces to the sources below. Review status is shown for every source.

Automated source check: the source was opened and its claims, dates and figures were compared with this dossier by an automated check. It is not a human sign-off.

Reuse, attribution and corrections

Text and data: Elgarde, licensed under CC-BY-4.0, canon release 2026.10.1. Credit “Elgarde”, link to this page and say if you changed the text.

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Suggested citation

Elgarde, “BMW N20 and N55 petrol engines (August 2011 to March 2012 builds): plastic oil filter housing oil or coolant leak”, known-defect dossier oil.leaks, canon release 2026.10.1, CC-BY-4.0, https://elgarde.com/defects/oil.leaks/

Machine-readable version

• This dossier as JSON https://api.elgarde.com/api/v1/defects/oil.leaks?lang=en
• Catalogue of all dossiers https://api.elgarde.com/api/v1/catalog?lang=en

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