Thread: So how do you get P0134 o2 (Bank 1 Sensor 1) Insufficient Activity and 950mV @ WOT?

Getting both things happening now, figured the extension harness was wired correctly for the front o2 after getting readings of 950mV @ WOT - I am not sure why I am getting P0134 then? How can you get both?

A narrowband o2 should change volt readings constantly, if it's not going from a low reading to a high reading, I gather that's not sufficient activity and might throw a code.

But I'm really not an expert on o2 sensors. Not even close.

The O2 is changing mV, it's just not changing fast enough. Given a steady dose of fuel (WOT) it will read that since the PCM is commanding a steady fuel constant. Otherwise the PCM is constantly searching for stoich (14.7:1 AFR) by adding fuel until the O2 reads roughly .500 mV, and then subtracting fuel until the O2 reads roughly .400. My explanation isn't to the number, but hopefully it will help you to better understand how things work. I was also told, by someone reputable, that the only way to see if an O2 is actually bad, is to test it with an oscilloscope. That's how quickly it works.

Please google and read up on what test the pcm performs to make the determination. But it's like the guys said..at some point it's not showing enough activity... likely the heater is going bad