I bought my 2000 4Runner about 7 months ago, and three days after I had it the check engine light came on. It was tripping a lean code so I assumed I had a bad O2 sensor but the code reader wouldn't give me any info as to which bank was tripping the sensor.

Anyway, I never got around to fixing the problem and then about 3 days ago all the sudden the check engine light turned off. I thought maybe it burnt out, but when I turn on my ignition it lights up.

The only thing that I have done in the last month is run some Seafoam through the engine, and clean the MAF sensor. I did the Seafoam about a month ago, and the MAF about 2 weeks ago, but there were no imediate results. Do you think that this may have fixed the problem? I wasn't getting the best gas millage before, about 15-16.5 and I haven't been able to see if that went up at all.

Do you think that the problem could have just fixed itself?

 

Yes, the check engine light can go away by itself. The code should still be stored though.

 

Well, you've only got 2 O2 sensors (1 pre and 1 post Cat) so you wouldn't have a lean code on an individual bank.

It's a good possibility you fixed your problem when you cleaned your MAF. It's a fairly common problem on these vehicles. Probably more common than an O2 sensor would be.

I'f I were you I'd judt keep driving it and wait to see if the light comes back on. If not then don't worry about it.

 

Weird..samething happend to me recently. Mine was on for a few days then went away....i'm thinking its likely my O2 sensor seeing on how i'm getting worse mpg suddenly or maybe its the cold weather? Wish I had a scan guage :sigh: