I can't answer your last two questions, though I'd be surprised if there isn't a relay. I replaced ours on our '08 at about 150k miles and had no further issues with the O2 sensors.

 

Thanks , I am guessing having a open reading on the leads to the heater portion of the sensor says Its a bad sensor. Do you remember what the relay was labled?

 

The heaters for the 2 "front" (located between engine and catalytic converters) O2 sensors are switched by a relay that is mounted on a printed circuit board internal to the fuse/relay/junction box, mounted on the left fender apron. That relay is not intended to be an individual replaceable part. There is also a 25A fuse dedicated to those heaters, labeled "A/F".

The heater power wires on the front O2 sensor connectors are Green (bank 1, sensor 1) and Yellow (bank 2, sensor 1). When the A/F relay is closed, those 2 wires are connected to battery positive via the aforementioned 25A fuse.

The Powertrain Control Module monitors each heater current and will set a fault code if not within design limits.

 

Thanks Michael . I am getting a open when I check for the resistance on the heater wires and that tells me the heater is bad. I saw in a video that there should be 14 volts on the pins that feed the heater but im guessing that it is not there all the time , only when ECU turns it on like you said . I all so noticed that my main thread title says CO sensor . ooops lol. I am not sure if it to late to change to O2 sensor but i t looks like a couple of people understand what I ment . Thanks again

 

I got a new o2 sensor and put in on 4 /29 and had the check engine light reset. Now time to wait and see if it comes back on. I will update in a bit if it comes back on or stays off. Thanks for the help all.

 

2 weeks since I replaced the o2 sensor and the Check engine light is still out . I think it is fixed. Thanks to all that helped me out , Roger