BMW E36 Oxygen Sensor (O2) Replacement DIY
At upwards of $220, the dealer price for replacing O2 sensors is quite absurd. Luckily with the help of some clever members of the BMW community, we were able to find out some interesting info that will save hundreds of dollars. As it turns out, NTK manufactures these OBDII O2 Sensors, sells them to Siemens and Bosch, who than resell them to BMW. However, if you buy the NTK brand name, they are a quarter of the price of the same sensors BMW badges and resells. However, these NTK sensors do require splicing. Simply cut the old connector off your used O2 sensors and splice it onto the new ones. Just take a look at this OEM BMW OBD2 sensor, and look at the NTK stamp right below the BMW logo.
For OBDI models, the Bosch replacement part is quite cheap at only $55, and we only have one sensor to replace unlike the 96+ OBD2 e36 models which require four sensors.
You’ll need the following parts and tools to complete this repair:
4x Oxygen Sensor Will replace BMW Part # 11781427884 ( for 96+ OBDII cars, you will need four sensors total, 2 pre cat, 2 post cat.)
Or, depending on your model year:
1x Bosch 13231 Oxygen Sensor Will replace BMW Part# 11781735499 (For OBD1 1995 E36 3 series, you only need one sensor.)
O2 Oxygen Sensor Flex Head Wrench You’ll need a crows foot type wrench to fit over the O2 sensor wire
Anti-Seize Lubricant Will make your life much easier when you have to remove your sensors in the future.
BMW recommends replacing your O2 sensors every 100,000 miles. However, it’s not uncommon to see them fail before than. Failing O2 sensors will cause inaccurate reading by your ECU, can damage your catalytic converters, decrease fuel economy, as well as cause other issues.
To replace your O2 Sensor/s start by jacking your car up, at all four corners. Be sure to take care, and use proper jack stands while completing the job. Always verify the car is securely raise before working below.
If you own an OBD1 1995 vehicle you simply have to replace one O2 sensor at the Y connection of the mid pipe. O2 sensors are notoriously hard to remove, the O2 Flex head wrench will make the job a lot easier for you. The task for OBD1 cars is fairly straight forward, and the sensor is assessable with out removing anything at all.
For our OBD2 brothers, the task is both more expensive and labor intensive.
Below you can view the location of the single obd1 O2 sensor located on the mid section of the exhaust(bottom), vs the OBD2 mid pipe (top) with the two post cat O2 sensor locations.