Hello everybody!
I have a question and I hope that you all can help me with it. Last Saturday, we were driving home in the rain and my wife noticed that the VSC/ TRAC OFF light lite up and so does the chech engine light. It stay on all day Sunday. I thought that since it is off I will pressed the VSC button under the dash to correct this problem. The light did not go off. Then on Monday, I cranked up the car and I noticed that both lights has gone off. We have a 04 RX330 with 45k on it. Does anybody knows what is going on and should we take it to the dealer and have them check it out. Thank you all in advance for your help. I have learned a great deal from reading the forum. Thanks again.

 

No, don't take it to the dealer. Likely it was something like a gas cap or some other issue. Generally in the case of my RX300 and it resetting it is a P0171 lean error, can be the temperature, a bit of bad gas, but many years ago in Mexico City I saw this happen and it would reset itself. If you are curious, I would suggest stopping by an AutoZone and getting the code read (it should still be in the computer) with an OBD2 scanner (the port should be just below your left knee).

 

This happens on my RX330 all the time - whenever the temperature rises by about 10 degrees or more. Seems the car measures the pressure inside the gas tank to ensure the system is air-tight, and is not leaking any gas fumes into the atmosphere (for emissions requirements only).

As it all has to do with the car reading a small negative pressure in the tank, there are lots of things that could potentially trip it off, including a non-airtight gas cap. If the pressure reads wrong, the ECU thinks the gas tank has a vapor leak, and lights up the VSC/CE lights to indicate an emissions error.

In my experience, it will eventually go away on it's own.

 

What you want to try is this: Turn off the car, remove the gas cap, and then retighten it. Then turn on the car and drive for an hour. If the lights go off and stay off, it was the gas cap doing funny things.

 

run the codes at autozone, it happen to my sister's car a month ago, it was the sensor (the one under the car, not the front). it was about $400 installed OE sensor at a local mechanic.