O2 Sensor Error Fix (Bad Fuse)

Materials Required

  • BMW OBD2 Scan Tool
  • Appropriate Size Fuse
  • Fuse Removal Tool
  • 8MM Socket

Scan For Error Codes

Using a BMW capable scan tool, scan for engine codes. If all of your O2 Sensors are showing bad at once, this DIY guide should fix your issue.

Codes: P0031 P0037 P0051 P0057

Disconnect Battery

Disconnect the vehicle's battery to ensure safety while conducting this job.

Open Hood

Open your vehicle's hood by pulling the latch.

Remove Cabin Air Filter Cowl

Remove the cabin air filter, HVAC cowl and all covers in the way of accessing the ECU. You should only need an 8MM socket for this.

Locate ECU

Locate your BMW's ECU. On LHD vehicles, it will be on the passenger side under the HVAC cowl. On RHD vehicles, vice versa.

Unlock ECU Cover

Unlock the ECU by sliding the locking latch to the left.

Unlatch ECU Cover

Unlatch the ECU cover by pressing/pinching the retention tabs inwards. This will completely loosen the cover so you can remove it.

Remove ECU Cover

With the ECU cover loosened, simply lift to remove it.

Locate ECU Fuse Box

Locate the fuse box pictured above. This fuse box contains the fuse that controls all four O2 sensors.

Unlatch Fuse Box

Unlatch the fuse box by pulling up and unseating the retention clip.

Unseat Fuses

Unseat the fuses by pulling them apart from the female end of the box.

Unlock Fuse Box Lid

Unlock the fuse box lid by using a pick tool to depress the retention clips (circled) and slide the lid back.

Remove/Replace Blown Fuse

Remove and replace the fourth fuse down. This fuse controls all four O2 sensors and typically shorts out if any mechanical work has been done.

Re-Install Fuse Box

Re-install the fuse box after replacing the blown fuse. Simply put the lid back on and press the fuses back into place.

Reinstall ECU Cover

Reinstall the ECU cover by re-latching and locking it into place.

Re-Installation

Re-install all components in the vice versa of removal. i.e cabin air filter and cowl, covers etc.

Reconnect Battery

Reconnect your BMW's battery.

O2 Sensor Error Codes Gone!

Using a BMW scan tool, confirm all O2 sensor related codes are gone. Note you may have to clear any pre-existing codes, so don't be concerned if you see any present at first.

DIY Complete!

Good job replacing your faulty fuse! Be sure to keep an eye on your electrical system for any future issues.