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64 01 25_INTERMITTENT HUMMING NOISE

SIB 64 01 25
INTERMITTENT HUMMING NOISE
☐

2025-02-28

THIS REPAIR IS MOBILE FRIENDLY

MODEL
F97 (X3 M Sports
Activity Vehicle)
G20 (3 Series
Sedan)

F98 (X4 M Sports Activity
Coupe)
G29 (Z4 Roadster)

G01 (X3 Sports
Activity Vehicle)

G02 (X4 Sports
Activity Coupe)

SITUATION
The customer may hear an intermittent “humming” or “foghorn” type sound in vehicle. It sounds like a low
hum that last for only a few seconds.
This can occur with the engine operating or may be heard for up to one hour after engine shut down.

CAUSE
This hum noise may be caused by the expansion valve of the air conditioning system.
Other noises may occur in these vehicles with different root causes:
For a whistling noise heard above 40 mph that is loudest with the sunroof in the vent position, see SI B64 01 21
For a clicking noise from repeated activation of the recirculated air flap, see SI B64 02 22
For a groaning noise heard from within the heating and air-conditioning unit in the center of the instrument panel
when either a ventilation flap, air stratification flap or the recirculated air flap moves to a different position; see SI
B64 04 22

CORRECTION
The expansion valve moves internally in response to system pressure/temperature and can occasionally make
noise. Explain cause of noise to customer.
Replace the expansion valve in cases where excessive noise occurs and is confirmed

PROCEDURE
1. Confirm the customer’s concern.
2. Check the vehicle for related stored fault codes.
3. Perform standard system diagnosis to verify the issue.
4. Replace the expansion valve only in case of excessive noise. If contamination is found when replacing the
expansion valve, then the air conditioning system should be flushed.

PARTS INFORMATION
Parts are only required in those situations where it is determined that there is an issue with the
corresponding system’s components.
To determine the part number(s) that applies to the specific vehicle being repaired, enter the VIN / Chassis
number into either ETK or AIR, this will consider the specific equipment and/or options that are fitted to the
vehicle.

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Additionally, other materials and small parts that are not specified above, such as fluids, lubricants, one-time
use screws, nuts, and seals, which must be replaced or installed (according to the ISTA repair
instructions/ETK/AIR), are to be selected from the Electronic Parts Catalog, and/or other approved BMW
Group’s resources according to the respective vehicle type. Invoiced these items separately under the
Repair Code listed in this bulletin.

CLAIM INFORMATION
This Service Information Bulletin provides technical, diagnosis, and repair-related information.
Damage and/or issues caused by outside influences are not covered under the BMW limited warranties.
Eligible and Covered Work/Repairs
Repairs that address a verified defect in materials and/or workmanship are covered under the terms of the
BMW New Vehicle Limited Warranty for Passenger Cars and Light Trucks.
To submit a claim, please follow the established and applicable warranty policy and procedures
(Labor/Part/Sublet – Bulk supply materials) that apply to the repair being performed.
Refer to AIR for the claim submission’s line item Repair Code.

BMW Group’s AIR Application Resource for Flat Rate Labor Operation Codes
To obtain repair-related labor operation codes (including diagnosis*) and the corresponding flat rate unit
(FRU) allowance information from the BMW Group AIR application resource, enter the Chassis Number (last
seven (7) characters of the VIN), and click on the “Search” icon. If the “Vehicle Selection” window displays
two or more model possible vehicle choices, select the applicable Model, or enter the full VIN (17
characters) instead to proceed. Click on the “Flat Rate Units” button and enter a flat rate labor operation
code description or number in the field to the right, click on the “Search” icon to display the corresponding
listing of “Flat rate unit group details” that are available.
(*) Based on which one applies to your center, please refer to SI B01 01 20 or B01 07 20 for the applicable
procedure for documenting, claiming, and explaining, on the RO and in the claim comments, your diagnosis
work time (WT), job/repair work time (WT), and the vehicle repairs your center performed, unless otherwise
required by State law.

FEEDBACK REGARDING THIS BULLETIN
Technical Feedback
Warranty Feedback
Parts Feedback

To submit feedback for the technical topic of this bulletin: Submit your
feedback in the rating box at the top of this bulletin
To submit feedback for the CLAIMS section of this bulletin: Submit an IDS
ticket to the Warranty Department, or use the chat available in the
Warranty Documentation Portal
To submit feedback for the PARTS section of this bulletin: Submit an IDS
ticket to the Parts Department

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