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Topic: O2 sensors revisited (Read 771 times) previous topic - next topic

O2 sensors revisited

Seeing someone's post about O2s I wanted to ask a a few questions about my problems and try to get some help while I'm still finishing up my car.

I don't have O2 sensors wired in right now. They are physically in the pipes, but not connected. When I do connect them in, the engine will not start. Doesn't matter if it's hot, cold, a few minutes, hours, or days later. Just won't start.

I know that I need to pull codes, and I will in the next few days...and I think I will try to replace the O2 sensors with new ones if I can do so without killing my wallet.

I've yet to locate another dash harness, but when I do, I'll have pretty much everything done, save for putting that harness in. I hope to have the O2 issue figured out by then, as I'm looking forward to driving it soon.

Oh yeah, it's a 5.0, 2.5" off road x pipe and 2.5" flowmaster cat back system, except there are not cats obviously. The O2s are old, and banged up. I wouldn't think for a second that they are in perfect working order...with that said, is there a way I can test 'em with a meter?

Be easy, I'm no electronics expert.. :hick:
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

O2 sensors revisited

Reply #1 –
I'd reset the computer and then try it and if that didn't work I'd either test the o2s or buy new o2s that may fix the issue.

O2 sensors revisited

Reply #3 –
Thanks...will definitely have to look into that on my next day off.
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

O2 sensors revisited

Reply #4 –
I'd replace them just by virtue of them being banged up. In addition to other contents, they contain a ceramic element, if that's cracked or rattled loose, they'll be junk.  They also need to breathe, usually they take air in for reference through the back where the wiring goes in.  I've seen where somebody taped up the wiring from the body to the connector and they wouldn't work at all. Last, be sure that the harness connector and the O2 connector are pinned properly.  If you've done any wiring there, it's possible for the heater circuit power to be feeding back to the PCM, and the PCM won't appreciate that at all, likewise if heater gound is switched for signal return (both black) you'll get strange problems.  One more thing I'd check is vref quality.  At your MAP, TPS and a few other places I can't think of, you should have 5 volts. You can have 4.85 to 5.1 anything else is a problem.  And just about any kind of situation where vref gets screwed up (like a short to power or backfeed) will make the car not start.  I once had replace mine and because clearance is a problem, I snipped off the wiring. The ed thing started g out OIL! It had run down the harness and filled the reference chamber.