lost bane
Just pulled 5min of diagnostic data, twice, from up/down O2 sensors - part of troubleshooting a P0420 error code. Opinions on whether both sensors need to be replaced?
It looked fine at the start, but I don't like those sustained peaks and valleys - seems like dirty data.
Also what is going on with sensor 2, it's only showing 1.275V straight across. Is this a sign of bad wiring, probably what threw the code in the first place?
lost bane
Data from an 8 minute test drive, doesn't look good for either sensor
remote fulcrum
Downsteam sensor looks shot if the flatline ain't obvious enough. P0420 also only applies to that one. Upstream sensor is specifically for measuring afr/lambda
pallid canopy
Bingo ^^^ and if this is the one where you just had the cat off, this is good news. Decent chance you can replace the downstream o2 sensor and that clears up the p0420!
lost bane
Does the waveform on the upstream sensor (blue) look normal? Any chance that one needs changing too? I kinda got it ... Wet, and wasn't sure if it would be fine now that it's dried
pallid canopy
To my eyes that actually doesn’t look out of spec - and I was worried the soap would contaminate the sensor. Happy to see sharp peaks on the waveform.
lost bane
Thanks that would be great news. I'm gonna put a few hours of driving on it this weekend, and if just the rear sensor is bad it doesn't sound like there'll be any problems
Oh in one of my logs today, upstream sensor hit '0' a few times, that made me think it was probably bad - is zero possible?
unique basaltBOT
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pallid canopy
I see the waveform tapped 0 a couple times there. Yep, it’s possible, all that’s really happening is you’re seeing a simulated reading of the voltage anyways. The important detail is that it cycles, and doesn’t hover around any specific voltage for a period of time