FYI

Posted moons ago about my 99 getting an SEL out of the blue, at 29K miles.
Turns out my 99 is one of the Cali-spec cars with the sealed ECU that you can not access to get "the ECU code" or to reset...
So...
Had to take it to the dealer and have them run the Consult diags.

Consult picked up a PO158 code - bad O2 sensor, rear.

Dealer replaced under warranty.

Within a day the SEL light was back! Finally got an appt to get back in, Consult shows PO158 again...

Turned out that the tech replaced the WRONG O2 sensor, swapped out the front when he should have done the REAR.

Got second new O2 sensor free!

FYI (per repair order - which could be bass-ackwards)
Front O2 sensor, P/N 226A1-4L715 Oxygen Sensor $57.20
Rear O2 sensor, P/N 22691-4L701 Heated Oxygen $115.44

HTH someone else.