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Of course I would assume my B2S2 needs replaced, but why 4 different codes for one issue? Is there something else I need to do or should replacing this one sensor solve all 4 codes?
For the TL, there are four different O2 sensors: two located before the cats (upstream) and two after (downstream). Specifically, the one to the rear of the engine and before the cat is considered bank 1, sensor 1 or B1S1. The sensor after the cat on the same side is considered bank 1, sensor 2, or B1S2. The sensors at the front of the engine are considered B2S1 and B2S2, respectively.
Front, bottom. Relatively easy to access but somewhat cramped. An O2 socket makes it much easier to remove. Otherwise you have to use an open box wrench due to the cable coming out the back. I believe it's a 22mm.
If you got the P0420 code, consider resetting the ECU before you go replacing the O2 sensor though. If it continually reoccurs, then change it. If it still happens after that, you may have a bad cat or too rich of an air/fuel mixture.
02-25-2019, 02:13 PM
