Hey guys new to the forum and to the Lexus brand as well.

So the story goes I just bought a 99 RX 300 with 196K miles on it for a really cheap price and it runs amazing, only problem is that it throws the P0171 code.

The previous owner had replaced the catalytic converter, both O2 sensors, the muffler, and also the knock sensors as well.

I so far have replaced the air filter and cleaned out the MAF sensor following the guide listed here on the forum. I have also used the CEL diagnostic tool that I have to monitor the issue and all my monitors come up fine, except the EVAP monitor so far.

I can provide data on any of the sensors, fuel trims, etc.

Thank you in advance!

 

Welcome to CL.

As it is only on one bank ... I would investigate after the split ... Sometimes during a repair folks take the cheap turn and do not get fresh gaskets and that can introduce air in the system. Could be a bad sensor at the exhaust end too.


Salim

 

check all your vacuum hoses and also all connections from your airbox to the throttle body. A smoke test can be useful.

 

Okay so this code has gone away, but now I'm getting P0330 & P0335.

This is weird because the previous owner said they had changed the knock sensors, but they also said the gas has sat in the tank awhile.

Any ideas? I'm leaning towards bad gas. I have put in a chemtool fuel cleaner in the tank and added some more 91 Cheveron gas to the tank no idea what was in it before.

 

Crank sensor? Sounds like electrical gremlins. Was it ever in an accident?