huh - the scanner condemned the downstream O2 sensor (from mode 06 data thanks to Ranger). Still can't get any voltage out of the IAT but it does throw a code when disconnected or jumpered and seems to have under 1kohms when measured with my super craptastic meter.
Oh, and the wideband shows a near perfect 14.9 through nearly all driving conditions, so it's not actually running rich despite the long term fuel trim being kinda high (8% or so cruising, 10% or so when on the gas a bit).
Did you replace it?
Ranger50 wrote: Did you replace it?
It? The IAT or the O2 sensor? The answer is neither. I have two little kids and a pregnant wife. I work in one hour intervals. I finished my diagnostics at around 10. I'll call Chrysler to price the O2 sensor tomorrow. I am still worried about my long term fuel trim numbers being so high, though,
In other words, my O2 is bad AND my injectors are clogged?
Your LTFT is ok, not great but ok. I meant the IAT. No need for $120 o2's yet.
Huh. See, I was going to take the opposite route and assume that my manual measurement of the IAT was good enough to ignore the software and that the mode 06 condemnation of my O2 sensor on both rich and lean sides was where to start. Chrysler apparently doesn't give out the O2 curves to the scanner, so without a sillyscope (used to have one) I was trusting their self diagnostic, and especially since there were two limits and both were failing for the same sensor.
Downstream or 2/1 o2 is just to monitor the cat and making sure that the cat is working properly. Pretty much as long as it stays switching at about a 1:2 or 1:3 rate to the upstream o2, it is working OK. Just because it fails a monitor doesn't mean it is bad. You may have not driven the vehicle through a complete cycle, so it shows failed or incomplete. Until you get a real hard code, I wouldn't worry about it being failed by the monitor.
Well I know that I've done a complete cycle. I drove it all around last night while on the scanner and shut if off and restarted too, the tests all reran dozens of times, and each time the downstream O2 sensor failed at least one of the tests for being lazy. So the downstream O2 sensor doesn't affect drive-ability at all?
OK, I can sorta buy that, but the IAT thing puzzles me. If it were bad, wouldn't it be running rich? The wideband says it's not. Other than the scanner software not getting voltage from it, I have no real symptoms from it. I guess I don't trust the software. Maybe that's bad.
See, I should have stuck with the O2 sensor - the new IAT measured exactly the same as the old on at ambient, in the freezer and in the car. No change. Time to pony up for the O2 sensor I think.
If you change any O2 change the upstream one the downstream doesn't do anything with fuel control it just makes sure the pre cat is there like Ranger said. The pre cat O2 might be defective and not throw a code but that is a long shot
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