97 MPV CEL Flashing

[CrissCross]

Hello All,

I recently had our 97 MPV in for a 15 point oil and lube including replacing the air filter. After that I topped off the fuel and added a STP Gas Treatment. Then drove it home about 25 mi. The next morning the CEL came on and is flashing. I was bothered. I stoped pulled over and checked to ensure that some one didnt goof and forget the oil plug. All of the fluid levels look ok. The vehicle drives just fine no cutting out not running hot nothing . Runs great. So I took it to be scanned at AutoZone. I was told it was a 02 sensor. a missfire and or a vacume leak. I check all the wires and all looks ok. Cant seem to find a vacume leak. Is it possiable that the fuel additive could have cause this if so should I drive it till the take is almost empty then try a new run on a fresh tank of gas or do you think that it is more likely that their is something wrong and if so what is the likely hood.

This is a 1997 MPV ES with about 123000 miles on it.

Any help would be great. Thanks in advanced.

[12Ounce]

Did you get the actual alpha-numeric code?

I would guess P0031, but you need to make sure.