Genuine BMW Bank 1 Lambda Sensor (B58 Gen1)

Product Overview

The upstream oxygen sensor is responsible for measuring the air-fuel ratio in the exhaust gases before they enter the catalytic converter. It sends real-time data to the Engine Control Unit (ECU), which then adjusts fuel injection to ensure optimal combustion, fuel efficiency, and emissions control.

Technical Specifications

• Part Number: 11-78-8-644-371 (11788644371)

   

   

• Manufacturer: Typically manufactured by Bosch (often cross-referenced with Bosch part 17404 or 0258027104)

   

   

• Type: Wideband (Broadband) Heated Oxygen Sensor

   

   

• Position: Upstream (Front / Pre-Catalytic Converter)

   

   

• Connector: 5-pin oval connector

   

   

• Cable Length: Approximately 375mm to 400mm (depending on the specific revision/brand)

Primary Vehicle Compatibility

This sensor is widely used in BMW models produced between 2016 and 2021. Key applications include:

• 1 Series: M140i (F20/F21)
  
  
  

• 2 Series: M240i (F22/F23)

   

• 3 Series: 340i / 340i xDrive (F30/F31/F34)

   

• 4 Series: 440i / 440i xDrive (F32/F33/F36)

   

• 5 Series: 540i / 540i xDrive (G30/G31)

    

• 7 Series: 740i / 740i xDrive (G11/G12)

   

• X Series: X3 M40i (G01), X4 M40i (G02)

   

   

Common Signs of Failure

If this sensor fails, you may experience:

1. Check Engine Light (CEL): Often with codes related to "Oxygen Sensor Signal" or "Mixture Control."

    

    

2. Reduced Fuel Economy: The ECU may default to a "rich" fuel map to protect the engine.

3. Rough Idling: Inconsistent data can cause the engine to stumble at low RPMs.

4. Failed Emissions Test: Incorrect air-fuel ratios lead to higher tailpipe pollutants.

    

    

Note: Because this is a precision electrical component, it is generally recommended to use the Genuine BMW or Bosch OEM version to ensure the ECU receives accurate voltage signals.