P0420 reading

Check engine light came on for the first time since I bought the car. P0420: Catalytic Converter code. I’m wondering if it could be anything else.

Probably unrelated, but I spilled a fair amount of oil onto the engine last week. I mopped it up as best I could. That couldn’t have affected anything, could it?

Could an old 12V be the culprit?

How often do the sensors go bad and pop that code?

I am reading with a fixassist 3020 from innova because it is what I could get today.

Not sure if anyone here can make sense of any of those readings, but figured I’d give it a shot.

Thanks for your time.

 

It’s got 265k or so on it. Not sure if the sensors were ever replaced, but doubtful. That was my first thought. The feller I bought it from never got the MFD board 60 pin connector reflowed, so I assumed he didn’t do much else DIY repair. The maintenance reports he gave to me never mentioned it I don’t believe. So you think it is a better idea to replace a sensor first and see what happens?

 

I feel like it definitely consumes engine oil between changes to some degree, but I haven’t actually measured the amount. Will do next change. I usually go for 4-5k miles on full synthetic before changing.

 

I got some live readings, and was wondering if this looks off: the a/f sensor is staying way below what the “normal” range is (3.0-3.35 volts) and rarely goes about 1.0v. It doesn’t fluctuate much and the downstream oxygen sensor fluctuates quite a bit and stays high, over .55 volts. Is there something wrong with my A/F sensor you think?

 

I’m using fixd, and it specifically says “a/f sensor” for the reading, not oxygen sensor 1 or any other misnomer for the part. I drove on the highway for 20 minutes to get those numbers, but very little about the a/f sensor readings changed during that time. Here and there would be a jump but it stayed pretty close to 1v. I haven’t checked fuel trims yet. There is literally nothing coming out of my exhaust that is visible whatsoever. It doesn’t smell any different in any way (don’t worry, I’m not sticking my mouth on the tailpipe). I’ll check fuel trims and post what I find.

 

What’s funny is catalytic converter tests all pass. But I am getting p0420 error. And that is the only thing that fails the emissions test. It came on and went away and is back on again. SOMETHING isn’t right. I wouldn’t be surprised if it was cat, but I’m not some rich guy who wants to throw 2k at a guess (I drive a gen 2 prius), you know?

 

OH, you are probably looking at the original images I uploaded. That tool was from autoZone and was incapable of providing live results. I got a new scanner and uploaded screenshots of the live feed. I have videos of it but I’m not sure if I can post them because they are long.