Tuesday, February 21, 2012

Check Engine Light on a 1996 BMW Z3 - PART 2 - O2 Sensor replacement (P1186)

O2 Sensor is on the passenger side.

Car jacked up - O2 Sensor is on the left side underneath
Close up of O2 Sensor in the exhaust
I went to Autozone and had them read the code on my 1996 BMW Z3.  See my post on the location of the OBD connection on a BMW Z3.The code showed a P1186, I researched the code and found it is an "O2 Sensor Heater Control Circuit" (Bank 1 Sensor 2). So I searched some more and found that I need to replace my O2 Sensor on my BMW Z3. Where is the O2 Sensor on a 1996 BMW Z3. On the 1996 BMW Z3 the O2 Sensor is located on the right (passenger) side of the car underneath and towards the front on the side of the exhaust pipe near the front Exhaust manifold and in front of the Catalytic converter. It is actually in a good location on the side and not on the top so you can get a wrench on the (22mm) head. I recommend a 22mm wrench as opposed to a 7/8in wrench due to the more exact fit. the 7/8 has enough play in it and the sensor is so tightly installed that you may strip out the edges of the sensor nut head. (which I did). See my post on removing a seized or locked O2 Sensor from a BMW Z3.
Side view of O2 Sensor
First thing your need to do is jack up the car. getting under it can be tight I recommend ramps or at least getting it up off the ground to get jack stands under it, i used two by fours to get it up enough to get my floor jack under it. Once up you can see the O2 Sensor from the Drivers side by looking under it and seeing exactly where it is located. You can see it clearly in the picture on the right showing where the sensor is located.
1). Exhaust Manifold to exhaust pipe. 2). O2 Sensor. 3). Catalytic Converter
Once the car is up you can easily see the (2) O2 Sensor in the side of the exhaust pipe. Notice how the sensor cable is connected at the top. It is easily remove by just gently pulling it out of it's socket. You can use a flat screw drive to reach up and get to it and gently slide the connection out if needed.
1. Electrical Connection on O2 Sensor
Take note of the new O2 Sensor, and the connection. The new O2 Sensor will have anti-seize grease on it and if not use some prior to putting it in.
New 1996 O2 Sensor
Screw the new sensor into the opening being careful to not touch the ceramic end of the sensor and not getting anti-seize compound on the end of the sensor. Tighten the sensor to 40ft pounds of torque. Once completed lower the car and take it for a test drive and then recheck under the car for any leaks (should be NONE) or anything else under the car that may be out of place. If the check engine light does not go off. remove your negative battery connection for 30 minutes to reset the computer then drive it and watch to ensure the check engine light does not come back on. If it does go back and have the codes read again and see if now something else is an issue and may be the root cause of the sensor going bad.

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