mikey00

That indicates you have a genuine problem. You already checked the hose behind the air box which is one of the most common causes. You may also want to inspect your gas cap real good, a poor seal could also be the cause. After that you need to get the codes to go any further. Some AutoZone stores will read them for free or pick up a scan tool. In my post above I mentioned I saw a tool on ebay for $16.99 plus shipping yesterday. That was the buy it now price and the seller had 66 of them. I went back today and I can no longer find them. What a difference a day makes. There are similar ones for $32.99 plus shipping. Harbor Freight also has inexpensive ones.

genijet

I went to Auozone and they used their OBD 2 checker and got the code: "P0171, system to lean bank (1)". They said to let it go "3 cycles" before seeing if the light goes out. I checked the gas cap seal. It looked ok but there was no pop when I removed it. After the 3rd cycle, I will get back to you. Any other suggestions?
Thanks for your continued interest. Carl

genijet

Autozone used their OBD 2 reader to identify this code: "P0171 system to lean bank (1)" and said to check it again after 3 full cycles of driving and cooling.
Back passengers have noticed a significant smell of gas after a half hour drive and the light was still on. What do you think?
Carl

Lexmex

That is what I was talking about earlier with regard to the 3 cycles. The P0171 error is a common error, in fact the most common error.

Most likely culprit is just climatological. However, you should also consider other than the gas cap the MAF sensor being dirty. That is the little black rectangular piece after your airbox held in by two screws. If the red diode and/or the two threads visible inside the piece get dirty, they can cause MAF issues. I remember a few years back when K&N oil got on mine that was I learned of the wonderful EFI fuse trick, which is what I recommend instead of just resetting the CEL with the scanner. Best thing I find to use now is electrical contacts cleaner or if not readily available computer keyboard cleaner.

mikey00

P0171 is almost always caused by dirty MAF sensor. I would clean using directions Lexmex provided. Here is also a link to a "how to" complete with pictures.
http://www.lexusownersclub.co.uk/kno...v2&id=152&c=11

genijet

I cleaned the MAF sensor as instructed even though it wasn't dirty and after driving the car for 2 miles, it went on again. I checked the fuel cap and it seems ok. But I did not get a pop when I removed it. What's next?
Carl

Lexmex

Carl,

What is your idle RPM when the vehicle is in D and you have your foot on the brake?

I am curious to see this as perhaps cleaning the IACV valve might be worth a shot here, if the RPM is off.

Only other thing then would be having someone with an advanced OBDII to see how the two O2 sensors before the main cat are holding up

I hate to see people have to deal with the O2 sensors. Despite no precats and using racing gas (unleaded variety, but high octane, as a cleaner) along with previously high sulfur gas, not so much as a peep out of my O2 sensors all these years, but that does not mean issues don't pop up with them.

Lexmex

One other thing that I know will bring up P0171 errors is fuel delivery. If there is anything dirty along the fuel lines, partially clogged injectors, you get a situation where there will be more air than gas in the air/fuel mixture and sometimes the ECM cannot adjust enough without throwing a light. It happens down here with vehicles that run the regular Magna gas, but can occur over time with other vehicles. One of my bosses had a CRV in which this occurred and we just gave it some Techron on half a tank of premium.

mikey00

Sorry to hear it wasn't the MAF sensor. I once read a post by a Toyota tech who claimed a P0171 was the most common code at his dealership and 99 out of 100 times it was the MAF sensor. As Lexmex already said now it could be anything in the fuel delivery system or even one of the 02 sensors. You may want to try a can of Techron in the gas tank to clean the injectors but it is kind of a long shot. You could also have a bad injector. All this gets a little difficult for the do it yourselfer to troubleshoot.
A vacuum leak or even a exhaust leak could also be the cause. You don't by any chance have an exhaust leak? 1999 RX had that piece of flex in the exhaust up by the engine that always seemed to fail.
You never did provide any more info about what transpired at the dealer. Being that they already told you you have a vacuum leak it sounds like they did at least some troubleshooting. Did they say how much it would cost or what they would do to fix the leak?

salimshah

It seems that no one caught this in your note...

Examine the rubber seal on the gas cap. After a short drive with right and left turns (to slosh up the gas in the tank, use your sense of smell.

Emission testing facilities also have a set up to check that the gas cap is working fine and for a small fee they can check it. If dealership is near bye take the cap in to the parts counter and let them take a look.

mikey00

It's not that no one caught the gas smell reference in the post, It's that we know it's not the gas cap due to the P0171 code. The gas cap would be P0440 or 442. It's most likely caused by a sensor delivering too rich a mixture or maybe even a leak or something else after the fuel pump but most likely not before the fuel pump.

genijet

I had a auto shop fix it and he found the Oxygen sensor bad.They replaced it and the car runs good.Thanks for all your help, I hope this info helps others. Carl genijet

genijet

I went to a local shop and the repaired it by replacing the oxygen sensor. Thank you for eveything. Please pass it on

hungeku

Lexmex,
Thanks very much for the tips. My Es300 had "check engine light" on for a while and the gas mileage was not as good as before. I followed your tips and found out couple of hoses which connected to the airbox were loose.
After tightening them up and resetting the engine light (unplug battery), the problem went away. Gas mileage improved (over 500 miles test).
Thanks again for the great advice.

ddell10

hi I am new and have a check engine light problem code 440,441and446on my 2002rx300.Can you give info on this