it started around 9 months or so ago when i got a SES light for P2A03 which is the o2 sensor on one of the headers. so i've been driving around with it like that and just dealing with the bad gas mileage. so today i decide to fix it myself because i have a couple of extra sensors and i take it to have the SES light read again to make sure there are no other problems. that's when i find out that there is a second code for P2A00 which is the o2 sensor on the other header. keep in mind, these are the sensors on the headers, not the ones on the cats. i believe they are actually called air/fuel sensors.

now im worried that there's something making the sensors go bad. i've done some reading on what would make them go bad but can't find any hard evidence. The car has around 50k miles, i run Shell premium gas (nitrogen enriched), and i have a full HKS exhaust with Vibrant HFC's.

one thing i have noticed is that after installing my Optima yellow top battery, the connections will corrode after a few weeks which my old oem battery never did. im leaning toward thinking the car has a poor ground connection. the trouble codes don't necessarily mean the o2 sensors are bad eventhough they could be, but that they are not reading correctly. maybe a bad ground connection could be screwing with them? maybe my HFC's and exhaust are creating back pressure and burning up the sensors? maybe the nitrogen enriched gas is bad on them? i just don't want to put new sensors in when it seems it's going to do the same thing to them. other than that all i can think to do is take it to a shop and diagnose the sensors to see if they're putting out any voltage or if they're shot. any help is appreciated.

 

I would take it to somewhere that has the proper OBD11 diagnosis interface and software, that will show if the O2 sensors are behaving as they should IE cycling between 0.4V and 0.9V at around 5 times in ten seconds, if the V readings are much different, or the switching times are much longer then the sensors are bad and need changing.

As for earthing problems, its possible that it has caused the O2 sensors heaters to fail, so this in turn will kill the sensors eventually.

Nor sure about nitrogen having an effect on zirconia sensors, would have to check.

 

any resolution to this?

 

I've been searching around and found on my350z that it is caused by a leak in the exhaust throwing off the o2 sensor. I'll know for sure when I change out the gasket.

 

Can you explain what this means? I have Cipher so I did some logs on my car (also getting p2a00 light that comes back after 300 or so miles after I clear it).
According to Cipher mine is reading around .7 to .9 V most of the time, but sometimes read as low as 0.09V. What does that mean?
Also..how can you differentiate between an exhaust leak and a bad 02 sensor (i.e is there any other values in Cipher logs that can help differentiate between the two?)