On the first cold (relatively speaking) day that I took my 2004 GX470 out, about 5 miles and 15 minutes into my drive, the Check Engline light, VSC, and TRAC lights come on. I purchased this GX about 3 months ago from a Lexus dealer with 104,000 miles or so and it has been solid since I bought it. Even when the lights went on, the truck didn't run any different, it idled and drove like normal.

I immediatly started the thinking the worst (O2 sensors, throttle body, etc.) and began searching. When reading about the changing the gas cap I remembered that my gas cap never clicked, it always seemed like it was loose, but I never thought anything of it. Well, I figured that before I go crazy, let me buy a new gas cap.

I went to my local Toyota dealer (2006 4Runner, forget the part number) and bought the gas cap for my GX. I put it on Monday evening when I got home from work. I immediatly noticed that when I tightened the new one, it clicked. When I went to unscrew it off, there was a little preassure. With a little force it came off. Before, the cap neither clicked or needed any force to unscrew. I was going to unplug the battery, but I wanted to wait and see if it would go off by itself.

Well, yesterday evening, i got home from work and me and my family took the GX to the doctor's office. Well, all the lights went off after I started it up. Since I changed the cap, I have not added any gas, disconnected the battery or anything.

Well, for $23 including tax, it sure took a worry off my plate. There was definitely something wrong with my old gas cap and from searching here, it is probably a common problem. If your lights come on, don't panic yet, spend the $23 and get a new cap and give it a few days.

 

Good fix. Mine was that lucky. Replaced the cap first then O2 sensor.