Vst, Trac Off, And Check Engine Light On

[wifey]

I have been lurking on this forum for years, usually I find the solutions to my problems via the search. I own a 2002 RX300 with 161k miles on it. We just had the timing belt, water pump and associated pieces replaced. After picking up the car, and driving it home. No problems arose, upon restarting the car for the next drive. I noticed the VST, Trac off and check engine light came on and stayed on. Checking this forum, suggestions were to check for a possible unattached hose behind the air filter box. I did that and could not find anything amiss. I even went so far as to disconnect/reconnect the two electrical plugs that go into the air filter box. I also disconnected/reconnected the hose that goes into the air filter box. I disconnected the negative cable from the battery, while messing around the engine compartment. I put everything back in its correct place, and reconnected the negative cable. Upon start up and driving the car for 20 miles the warning lights did not come on. My questions after all this write up; is what hose has everyone been talking about that sits behind the air filter box to check? And does lifting the negative cable reset the codes?

[uncle]

If you connected your car to an OBDII reader, it will probably tell you one of the primary oxygen sensors is bad. The result you see are sympathetic and false.

[DdSfJAbWnz]

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[colinh]

When my engine check light came on I discovered that I had forgotten to fully tighten the fuel cap. Can't remember if the other lights were on at the same time but I now I always toghten the cap until the ratchet clicks!

[Gidget300]

By sympathetic and false, are you meaning that the sensor is not bad?

[KeyKeeper]

Check the voltage before you proceed any further. Start the vehicle, turn lights, AC, wipers, stereo on. Let the car get hot and the electric cooling fans kick on. Measure voltage at idle at the battery terminals after fans have been on for a couple seconds. If you dont have 13.2v or more, your alternator is on its way out. The SVC/ABS/CEL will illuminate and throw all kinds of ghost codes out making you chase your tail. Its easy to verify the voltage is good/bad so start there first. If good, then plan on pulling some hair out.

[JSD]

Have the same problem. Unfortunately took my 2003 300RX to the local Toyota dealer to rotate the tires, another story about those maddening locking lugs. On the way home the same 3 lights came on. Service manager insisted that they did nothing other than rotate the tires. Called the out of town Lexus service manager where we purchased the car. His immediate reply: " Someone has been messing with the air filter." Returned to the Toyota dealership and after a phone call between the two service managers the Toyota manager said:"Of course we always perform a 24 point service check which includes the air filter." After 3 attempts each time the lights are off from 1 to 10 days but always come back on, the Toyota dealership refuses to do anything else. The problem is either un-metered air entering the intake system ie a leak or a bad sensor either way damaged by the service shop. With the exception that the lights are on, the car performs without issue. Of course, the problem destroys the cars resale value, but I plan to drive it 'til the wheels fall off. Lesson: Never take a Lexus to a Toyota service department not even to rotate the tires.

[uncle]

Buy a cheap OBDII reader and acess the codes yourself, record them, and reset. When and if the lights come back on, use the meter and see if the codes are the same. The VSC and Trac lights probbly mean nothing and are OK. You are looking for the code that identifies the real problem. It could be an air flow sensor (primary Oxygen sensor) or something else. In any case, with a reader, you can identify and either fix it yourself or have someone do it for you. A bad gas cap can cause a code,

[planman67]

JSD, I had the same problem 3 years ago. All three lights would come on and eventually go off. The Lexus Dealer said it was the gas cap. The previous owners, a relative, did all the maint on the vehicle but Lexus still could not figure out why the lights came on. The one thing I noticed is my gas mileage suffered cause it was not running at optimum when they were on. Finally, I went to AutoZone and they read the codes for me. Oxygen sensors, up-stream, both of them. I checked around and most places wanted between $300.00 and $450.00 to do them both. If you are handy at all, you can spend $11.00 for the socket, or rent it from Auto Zone, and do it yourself. I ordered the sensors off the internet and saved about $100.00, put it up on ramps and in 45 minutes the lights were off and have yet to come back on. Vehicle has averaged out now at 19 mpg city.

I would say the only other thing I did was let it cool and spray some penetrating oil the night before to help loosen them.

That is my experience on those crazy three lights.

[HerbieK]

OK, time to jump in on this thread. I have an 2003 RX300 with 113,000 miles.

When the check engine light came on, I took it to my local guy who had recently replaced the timing belt and water pump. He checked the codes, but had nothing, so I went to another local garage I trust. Codes showed a Bank 1 lean condition. Since plugs were way past due, I had them put in new ones at a cost of about $300. The three back plugs all were very carboned up, and the mechanic told me that was the sign of a bad O2 sensor. I found a Denso OEM (234-9009) part on Amazon for $100, and with the help of YouTube had it installed in about 45 minutes. Reset the codes and off I went. About 20 minutes later the light reappeared.

Now I am really flummoxed. I've inspected the air box, and found nothing loose. Any suggestions as to what I should try next, besides taking it to the Lexus dealer of course.

Thanks!

[uncle]

Buy a cheap OBDII reader, plug it in, and read the code yourself. It will tell you where the problem is. What code continues to reappear? Stop throwing parts at it, use the reader and address the specific problem.