Hi Guys, I have a 2006 ES - about a year ago i ran out of gas - every since then i had a CEL light with P0421 - I eventually took it to dealer to diagnose if it was a CAT or O2 sensor - they said it was front O2 Sensor.

Anyhow they wanted 350.00 installed (OEM) and I didn't have the cash.

Finally had a little extra dough, and last week I picked up a Bosch 15514 sensor and put it on - i unplugged the battery and the thought I was good but the code came back about 24 hours later.

then someone cleared it from me with the little computer and it came back in about 1 hour.

One thing I notice with new sensor is the MPG went down to about 1/2

Am I using the wrong brand of sensor ?

Dealer is no help, they just want to charge me 90 bucks to diagnose again - I paid them for that already - Geez !

The car has ran great - i just wanted the light to go away.

thanks in advance.