I just got my SES light on and checked the code. It was PC0138 and the read out stated to service emissions soon. I think the code is for an 02 sensor and is bank 1 sensor 2? I cleared it and the car ran fine the rest of the day without the SES light coming on.
I have a few ?'s. Is my 02 sensor about to go or is there a chance it was a one time thing? Also which 02 sensor is this? Is it pre-cat? Firewall bank?
Thanks. This is for a 1996 Sedan Deville.

The sensor is just a little sluggish. I have had that a few times and figured I'd take care of it if it became persisitent. Haven't seen it in over a year now.
Bank 1 Sensor 1 = right bank manifold
Bank 1 Sensor 2 = pre-cat
Bank 1 Sensor 3 = aft-cat
Bank 2 Sensor 1 = left bank manifold

Thanks I appreciate it. Bank 1 is the firewall bank correct?

Bank 1 sensor 2 is the sensor just before (in front of) the catalytic converter.

Thanks I appreciate it. Bank 1 is the firewall bank correct?
Yup, Bank 1 is right Bank (firewall side).