Danscorp

I have a 2000 RX300. All I did was replaced the factory air filter with a K&N filter and disconnected the battery this morning. Tonight, when I was driving it, I noticed the "Check Engine" light came on.

Is this consider normal for disconnecting the battery and changing out the air filter? Will the light go away within a couple of days or do I now have to take it into the Dealer to have them look at it?

The car seems to be running fine so maybe I just need a system reset but can I do that myself? Anybody know how?

Any ideas/suggestion will be much appreciated.

Thanks,
Dan

jeremyp111

I also have a '00 RX300 and I just had my check engine light come on a few days ago. I too also replaced the stock air filter with a K&N, but it was about 2 months ago so I don't know if there is any correlation. I'm going to have mine checked out at the dealer.

Lexmexico

Not that it matters now, but why did you disconnect the battery when installing the air filter?

I would go to an Autozone to pull the OBDII code out of the car's computer. If you get something like P0171, a fuel trim lean, nothing to worry about. Otherwise, pull the #13 EFI fuse, it is yellow from my memory, with the car turned off (no key in), and put it back in after about 10 seconds. This should reset your check engine light.

Danscorp

I love this board and thank you Lex! I did what you said and pulled the EFI fuse out for a couple of seconds and started the engine and the light went away If it comes up again, I will bring it to the Dealer.

Do you know exactly what the EFI fuse is for? I'm just curious.

Yes, I normally unplug the car battery everytime I work on my car. I guess a force of habit over the years to avoid accidentally shorting something out. In this case though, I thought when an air filter is replace with a better flowing one, the computer needs to be reset so that it can recalibrate the air/fuel mixture. If not, it will use its old settings which will defeat the purpose of switching out with a better air flowing filter. On my prior car, that was how they said to reset the computer and I just assume it's the same with a Lexus.

Lexmexico

Pulling the EFI fuse does precisely what disconnecting the battery will do. I generally only pull it during a check engine light. Others can also pull it to zap the transmission computer clean. The car will feel A LOT BETTER after you do this.

parula

Lexmex, tks, making note of that too! Sounds like sort of a reboot of the computer, nice.