Hi everyone,

I’m looking for the expected readings/specs for all 4 oxygen (lambda) sensors on a 3.0L V6 engine from around 1999–2000.

It seems like one of the cylinder banks is running too rich — possibly overfueling. I checked the data through the computer, and I can see that the left and right banks often show different readings on the O2 sensors.

I’d like to understand what the normal parameters/values should be for these sensors, so I can figure out whether they need to be replaced.

Thanks in advance!

 

I'd use the fuel trims.

Do you have DTC P1111 or P1000? You always have one of those.

Are there any other codes?

 

+1 on that. Here’s a good primer on how to use fuel trims for troubleshooting:


http://jagrepair.com/UsingFuelTrims.htm


I've never used O2 sensor voltage for troubleshooting but here’s a good guide showing what to expect:

https://www.innova.com/blogs/fix-adv...s-in-live-data


Just for giggles, I took a screenshot of my scanner:





This was on my ‘02 V6, at idle after a 30 minute drive. I forgot to note the time interval between each peak, but think it was about 1 second apart.

Note how only the upstream sensors are cycling up and down. The downstream sensors basically monitor the catalyst efficiency and health. The steady low voltage shows the cats are cleaning the exhaust. If the downstream sensors are cycling at a rate close to upstream, that means the cats are not doing enough cleaning and a code will be flagged.