1999 TL.
The mechanic :tonguefaw says that the only thing they had to disconnect/connect is the Bank 1 Sensor 1 to replace the pan. The P0141 is for the Bank 1 Sensor 2 Oxygen sensor.

How many miles should I drive and see if the CE light goes away? I did not have the CE light before replacing the oil pan.

 

Pull the clock backup fuse on the passenger side dash fuse panel for 2 min or so then put back in and start the car. If it comes back on id either check that they plugged the O2 sensor in or bring it back and make them fix it.

 

Well I tried this. But it did not work. The CE went off but came back on in 5 secs or so. Bummer. Looked under the car and made sure the O2 sensor is plugged into the catalytic convertor. Whats the purpose of the clock backup fuse?

 

Pulling the clock fuse is to reset the ecu. assuming everything was installed properly, reset should set the brain back to normal. If you did reset and the code still comes back, meaning something is actually wrong and needs to be looked at.

 

Ok finally got the CE cleared by replacing the O2 sensor. Weird how replacing the oil pan blew the O2 sensor. Doesn't make sense. May be two isolated events but it was hell of a coincidence. Hopefully it doesn't come on again.

 

Maybe when they removed it they dropped it?

 

Sometimes, with the lack of anti-seize compound, the O2 sensor will "weld" itself into the exhaust pipe from the shearing heat after a long time. So it is very easy to damage the O2 sensor in the process of forcefully removing it.

 

I had same problem when dealer replaced oil pan. Afterwards, CEL light up and P0141. I bought the OEM O2 sensor online $70 less than dealership. Gonna work on it today.

Question is: Why do they have to remove the O2 sensor to replace the oil pan?

 

Because you have to remove the part of the header it attaches to to get the oil pan out.