Just trying to narrow down some issues with the beast. I've been monitoring the 02 sensors and the 2nd bank sensor 2 has diffrent readings than the rest.
Bank 1 sensors and bank 2 sensor 1 voltages are always fluctuating in range, while bank 2 sensor 2 sits right at .775mv during most operation, it varies very little at all and the voltage changes around once every 10 seconds. The other sensors are constantly changing in parameters under all conditions.
I'm new to multi-02 systems and I've searched the forums. I'm just wondering what this steady voltage reading may be indicative of?

I'm guessing the sensor is on the way out. I'll check the 02 wires and exhaust for integrity, I just wanted to get some experienced opinions before I go throwing money at it!!!

Thanks!

 

This is the after cat sensor and it does nothing in terms of feedback for fuel management. All it does is tell the computer that the relevant cat converter is healthy. If something is wrong it will throw a code. Some poeple remove the post cat sensors and program them out with no ill effect, provided allowable by local smog law.

 

Swap it with the other post cat sensor and see if the trouble follows. That won't cost you anything. The sensor is either lazy or it might be telling you that there is something wrong with the cat.

 

thanks for the info. So basically the secondaries don't affect the air/fuel ratio, so as long as its within parameters ( no ses) the cat's "functioing properly".
As suggested I'll probably swap the secondaries to see if its the sensor or the cat thats causing it. High voltage = high 02 content, or a lean condition right?
It did throw a multipule misfire code and 02 parameter code about 10 days ago during a crazy butt thunderstorm that left about five inches of water on all the roadways. Every time it gets pretty wet out the engine runs a little rough. car has 98k on original plugs/wires, so I'm gonna start with those and ""HOPEFULLY"" no OPTI molestation is in my future!!!

Thanks again for the replys!

 

Appears that even with the SES light, there is no impact on A/F ratio from the after-cat O2 sensors.
No. 450mV is stoichiometric. 775mV in closed loop would indicate it is running richer than stoichiometric. In power enrichment (PE, often referred to as WOT) mode, 775mV might indicate an A/F ratio leaner than you want for peak power and peak torque. But in closed loop, its too rich.
What O2 parameter code did it set? Or was that also the one for low problems with B2S2?

 

I forgot what 02 code it was, and after 2 days when I tried to pull it back up with a scanner, it had cleared itself. Short term/long term memory loss much????
Anyway, the bank 2 rear sensor almost always stays right at .775mv, at WOT, idle, any condition. It reads .775 for about a minute steady and then will vary only slightly down to about .630 up to about .840 depending on throttle position. The voltage readings only change about once to twice a minute.
The upstream sensor is varying at the same rate and voltage habits as the other sensors in bank one, changing at a constant rate. I'm guessing this sensor is toast.

 

does your car ever miss, bog, or anything when it is hot, about after 20-30 min. after running? if so, im almost positive it is the 02...let me know