P0125 - Ugh!

After installing my Doug Thorley header last weekend I got a P0125. After Googling, I came up with a bunch of things. But, after searching on here, Toyota had their own reason for this code... the front O2 sensor / A/F sensor. Well, I ordered a new Denso from URD. I cleared the code via ScanGauge and put in the new sensor. Within 5 mins of driving the CEL came back on.

Is there something that I may not know, that I may have overlooked? Or do I just need to continue down the list until the CEL goes away?



Oh, I didn't disconnect the battery. I simply cleared it via ScanGauge. Could that be the/an issue?
Edit : Disconnected battery. Same issue.

 

I'd check for exhaust leaks.

 

Josh, I looked up P0125, and it is: insufficient coolant temperature for closed loop fuel control. This is not any where around the O2 sensor, but may be one of the temperature probes that connect to the engine. You have two sensors, one is for your temp gauge on the dash and one for the ECM or computer.

I looked the sensor you want on autozone and this is the link to it.http://www.autozone.com/autozone/parts/1998-Toyota-Tacoma-2WD/Coolant-Temperature-Sensor/_/N-ja5cpZ9gslt

There is your other sensor, this one is for the temperature guage. So you won't mix them up. http://www.autozone.com/autozone/parts/1998-Toyota-Tacoma-2WD/Temperature-Switch/_/N-ja5cpZ9gsmf

I think if you change sensor, you should see your light go out. GOOD LUCK.