GenVibe - Community for Pontiac Vibe Enthusiasts

2007 Vibe base manual 5spd
I was getting a catalytic converter below efficiency threshold code. I know this can be caused by bad O2 sensors. Unfortunately I was still under the impression cars had upstream O2 sensors. I trouble shot it as such. I have now learned about wideband AF sensors. My testing was pretty much useless, but I do believe the sensor was bad. I ordered both upstream and downstream denso sensors. After installing the new upstream sensor and clearing my codes the car seems to run better. I used to smell gasoline and was fairly certain it was running very rich. No more gas smell. I'm just trying to verify that I have things sorted and there aren't other issues. My downstream sensor seems to oscillate between 0.15 and 0.84 at idle. The upstream oscillates between 3.15 and 3.40. I was expecting both of them to be a little more flat. Long-term fuel trim runs at 2.34. short-term fuel trim has a sawtooth pattern oscillating between -0.75 and 3.1.

Are these acceptable values? with the long-term running at a positive 2 plus I'm wondering if somehow I still have a lean condition, meaning I have an air leak somewhere, or would unhooking the battery for a while to erase previous incorrect readings possibly help?

P0420 = converter nearly 99.99999% of the time. This code in and of itself says the o2 sensors are working, as they are determining the converter is below the established efficiency thresholds.

You also do have upstream and downstream o2 sensors... That said, the upstream sensor is usually a "wave" on the graph and the downstream usually sits flat, until you step on the throttle, then it should similarly mirror the upstream.

Edited to remove info on 03 models that doesn't apply to 07s and was misleading

zbyers wrote: ↑Tue Aug 25, 2020 5:57 am
You also do have upstream and downstream o2 sensors... That said, the upstream sensor is usually a "wave" on the graph and the downstream usually sits flat, until you step on the throttle, then it should similarly mirror the upstream.

That is true from 2003-2005. 2006-2007 the upstream sensor is called an air-fuel sensor or wide band O2 sensor. It is still called an O2 sensor, but instead of generating between 0.1v to 1.0 like a traditional narrow band O2 sensor, an A/F wideband sensor has to do with current and it works in the mv range. A code reader will show a range with 3v being near the center.

I've done my research on this, but what I haven't been able to find is someone with a Pontiac Vibe posting what I should see. generally I believe the upstream should now be more of a flatline, I'm just not sure how flat that line is supposed to be. I expected the downstream to be a flat line as well but I'm sure not getting that.