chris j vurnis

Could a "lazy" O2 sensor suddenly come back to life or do they just stay bad once they go bad?

This evening my car was suddenly peppier on the bottom end with crisper than usual throttle response. I haven't done anything differently. Always use the same gas, no major maintenance recently, nothing out of the ordinary. Weather has been the same all week.

I've suspected that I have bad O2 sensors since my car has been sluggish for a while. I changed the knock sensor a few months ago and it did help out.

Sean97SE

My ecu as thrown an o2 code before that eventually went away, so in theory, yes i guess they do, i actuliy i dont know becaus ei never replaced it or had it checkedout, i just reset the ecu and it never came back.

MrEous

iTrader: (11)

When you reset the ecu isn't that basically telling the ecu to fuhgettaboutit?

Jeff92se

iTrader: (82)

Do they do not. Could be an intermittant problem.

CEL could have gone on if the ecu saw a temp out of range voltage. But if it doesn't see it for like 50 turns of the ignition key, it wil reset itself.

chris j vurnis

50 turns of the ignition key? I guess that would be about a month's worth. Well, my car is still running nicely for the past few days. I cannot ever remember a time that it has run so good in the past 7 years I have owned this car.

I did replace the knock sensor a few months ago. There was an improvement right away with that change. Could it be that the dealer service guy didn't reset the ECU and now the ECU decided to reset itself for a complete improvement? That would be kind of odd but maybe possible. If that was the case, then I bet my knock sensor must have been bad for at least the last 5 years (since the time I actually started to care about and notice mods and speed) because my car has always been relatively weak under 3000rpms until this week. I just always thought that was the way the car was engineered.

I have read on this forum that knocks sensors have been known to go bad after 30K miles. I got 90k miles now. I know that when I got the knock sensor, the top end of the engine got better but even before the sensor change, it was noticeably stronger than the low end.

Wacky stuff.