Junior Member
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Join Date: Aug 2020
Location: RI, USA
Posts: 14
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Junior Member
Join Date: Aug 2020
Location: RI, USA
Posts: 14
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Another P0441 chase. A/F sensor at 0 volts?
Alrighty, another exciting P0441 thread, yay!
So, I bought '01 just a few weeks back. Clearly, the person I bought it off of had reset the MIL before I came to see it, because nothing was on during the test drive, but CEL and VSC / TRAC lights came on after my first couple trips since then.
I ended up buying a OBDLink MX+ once the lights came on, which is my first scan tool so I'm very new to using it (wish I had it for the test drive hehe) . The only code it is throwing is the P0441.
The vehicle runs well. Starts up quick, although it does idle higher than I would expect for longer than I would expect at startup. Nothing crazy, maybe 1200rpm. Idles at 650/700rpm at stop lights. I did notice while looking for vacuum leaks under the hood that a couple of the hoses aren't in great shape, and it's actually missing the 3" hose clamp after the MAF entirely, so I have some stuff on order for that. This alone could easily explain the code and the high(ish) idle at startup. I also bought a new gas cap from Toyota because I get a hard start ONLY after gassing up. I know this could be the canister / valve too, but I figured why not start with the gas cap for $30.
I was able today to plug the scanner in for my trip to the dealership, and monitor the O2 sensors readings... to my surprise, "Sensor 1" is never getting any voltage... like, at all. When I tried to graph it in the app, it didn't even register a reading for sensor 1. There was no flat line at zero volts, there was just no line at all on the graph for that sensor. I was really confused by this because by my (limited) understanding, I would imagine that no signal from the a/f would make this thing run horrible, or at least definitely throw a more specific code other than "pressure in evap system is off". There is no mention of it being in any kind of "default" mode that I can see. I have yet to get under the vehicle and check wiring / connections because it's raining out right now and I'm a driveway warrior.
I've searched the forums and the internet at large for "zero volts at air fuel sensor" and similar syntax, and haven't came across a thread where there was absolutely zero registration from Sensor 1. Just curious what it means to get no reading at all from an a/f sensor, and why it's not triggering a different code?
Thanks!
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2001 T4R SR5 4WD, auto, 189k.
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