I have a 99 Lexus RX300. My check engine light has come on 4 times recently. I am wondering if my car can not take the ethanol that is being put in the fuel and therefore is causing the light to come on. It usually comes on minutes after I refuel. This time it came on after 1/4 of a tank. When the light comes on, the car bucks. I have spent over 1000 dollars to fix and nothing seems to help. Would it help to run premium? Would it help to run regular gas without ethanol?

 

How about a description of what was tried/replaced for the $1,000?

 

I had the same problem. It is the gas cap. Does it make a sound when you open the gas cap? It should sound like opening a soda can. If it doesn't, it doesn't have suction or good seal. OEM gas cap is about $20?

 

Yea i bet it is the gas cap they can go bad.

 

Before spending any more money, go ahead and replace the gas cap if you haven't already.

 

Welcome.

When you mean ethanol, I assume your talking the 10% variety.

Have you had the vehicle scanned for OBD2 codes as that would help a lot to know what is going on.

If there is crud at the bottom of the tank, that can get kicked up and shot through your fuel lines, through the injectors, in the combustion and reach the a/f sensors triggering a check engine light, but in order for me to be more precise I need to know what codes you have.

Initially, knowing nothing else, I'd run some fuel injector cleaner in the gasoline.

Ethanol can, when it sits in the tank a bit too long without use, cause issues.

 

Do you by any chance run the engine while fueling?

I just had to ask as there are some who do.

Salim

 

Had the same thing happen to me, many times before I figured it out. And it was not to the tune of $1000.00. All I did was secure the cap after re fuel with only ONE CLICK. It has worked for months, no more CEL. I guess the gasket on the cap was getting flattened out if it was tightened to much, and lost it's seal. The difference between yours and mine was that my RX always ran good with the CEL on or off.

 

I vote for a new gas cap, too! I haven't had to change mine yet, but the dealer says it happens sometimes.

 

Our county here, requires an annual emission test. They screw in the cap ti a gauge and it runs a leakage test. So the cap can be tested.

Salim

 

Mine did that and it ended up being (2) o2 sensors

 

I have a 2001 Lexus RX300 and I am getting CEL for gas cap after refueling to a full tank and it comes on approx 50-65 miles and once I go to AutoZone to determine the CEL code ... it states Fuel Cap and they reset code and it's does not come on until another refueling at approx 50-65 miles.

I purchased a new one when I was having other EVAP issues earlier this year and I still had old one and put old on the last fill up and CEL code went away on its one but it came back on at approx 55 miles today.

Any suggestions?

 

OE or aftermarket gas cap?

 

I purchased an OEM cap from Toyota.

Code I am getting is P0442 ... states small EVAP leak.

What I don't understand is that I can reset the code and it will not reappear until another fill up. I am perplexed as to why the CEL does not come back on until another fill up after I reset it.

I have new OEM gas cap. I was driving with CEL on for about a month and one day the CEL went off on its own but reappeared on next fill up.

Anyone have any suggestions?

Many Thanks!

 

Since you stated "any suggestion" ..

The assumption that a gas cap needs replacement after the code is wrong. The error code only points to a system of malfunction. The issue then needs to be traced and it can be that more than 50% [pick any number] of the problems got fixed by replacing gas cap.

Leaks are hard to find and as the vehicle ages each hose/bend/connection is a suspect.

I would suggest getting "smoke test".

Salim