Hi Scotty,
I have a 2015 Tacoma with a little over 113k. My check engine light came on and the code read a bad O2 sensor. I replaced it and it came on again today. This time the code reads PO138- circuit high voltage (bank 1 sensor 2). Is it a bad sensor or is there something else going on? What do I need to check?
You'll be under the truck to replace the sensor. If you inspect the wires and they look good then replace the sensor.
"Oxygen sensor 2" are downstream oxygen sensors (after the catalytic converter)
You don't need to replace the upstream ones right now unless you want to.
Thanks jack62, I’ll check tomorrow after I get off of work
Ok, update on my Tacoma. Like I said it had the code PO138. I get off work today and go run a few errands and stop to get a new sensor and air filter. I leave from getting groceries and the check engine light went off. Would it still be smart to check the wiring and replace the sensor?
Since you've replaced the sensor it's time to carefully inspect the wires going to the O2 sensor.
P0138 is thrown when voltage at the sensor remains above threshold for 20 seconds.
Could be a damaged wire under the truck that's "shorting-out" intermittently
The sensor replaced was bank 2 sensor 2. This one is for bank 1 sensor 2. Would it still be a bad sensor that needs to be replaced? If so, should I go ahead and replace the other 2 sensors?