99es300

1999 ES300 and the check engine, VSC and VSC Off lights are all on. They came off for almost the entire morning (after refueling the previous day- something to do with that?) but now are back on. Anyone know what is up with this?

99es300

Ill check with AutoZone to get those codes first...

Pheonix

Good answer!
Let us know.

Tammy

Insure the fuel cap is sealed.

mark Grana

mine are on too. I went to Advance and did the diag. got code p0171 system too lean (Bank 1). Looks like a bad o2 sensor in the bank 1 side of the manifold which I believe is the one in the back next to the fire wall. Am planning to get a denso sensor off line at Oxygensensors.com and replace it myself.

99es300

Yep- that's it. I just got diagnostics and it is a code P0171- BUT WHICH sensor is bad??!! Is it the MAF (or whatever it is) or one of the O2 sensors? How do I know which one?? Thanks guys.

Also, do these sensors affect driving (the diagnostic said it was running lean- but how so?)

lexusk8

When the P0171 code is on, that usually means that one or both of the pre-cat oxygen sensors are going bad. Only way to find out is to test the resistance of the sensors when removed and see if it meets spec. It is OK to continue to drive with the P0171 error code on, but you will continue to get poor fuel economy (i.e. worse than 18 mpg).

99es300

Thanks for the reply- have you or has anyone replaced the sensors themselves (hard to do)? Is there some kind of tutorial on CL for it? Where are they located (the sensors themselves)? Thanks for the help...

lexusk8

You can try to do a forum search for a tutorial on replacing O2 sensors. It may not be located here in the ES forums (at least I don't recall it), but try the other model forums (i.e. GS, LS, RX, etc.)

99es300

Well does anyone know how to test the O2 sensors to find out which one is the bad one?? I'm pretty new at this (and my gas mileage has gotten bad)... thanks

miltonlin

Here's what manual says for checking the 3 o2 sensors

miltonlin

Hope this helps

saltyreefs

are those resistance numbers are the same on all lexus es300 models, on checking the o2 sensor?

miltonlin

the pics were from the official 1999 ES300 repair manual. But for any 1MZFE engine at least from 1997-2001, I don't see why they would be different.

99es300

i dont know if i am slow or what. what setting do i switch the ohmmeter to? (i.e. 200k, 20k, 2k???) also i am following the instructions from the above post (repair manual) and am not getting any kind of reading on the meter...