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VSC light 1999 Lexus es300

For no apparent reason my VSC lights come on. I took it to one repair shop and they said my catalitic convertoer need to be replaced??? I took it to a dealer they said it was a faulty gas cap. I replaced they cap, but this did not fix the problem. If I turn the car off and start it again the lights go out. Any suggestions?

On some cars, the Vehicle Stability Control warning light will come on along with the Check Engine Light (CEL)–for reasons that escape me. The need to replace a catalytic converter and/or having a faulty gas cap are both situations that would trigger a CEL (and possibly a VSC warning light), but if the CEL is burned out, you would not be seeing the full picture, so to speak.

Step One: Verify that the CEL light is still operative! When you turn the ignition key to the “on” position (the position before the “start” position), the CEL should illuminate briefly. You may need to do this a few times to verify whether the CEL is still working.

Anyway, my thesis–subject to revision–is that you CEL may be burned out. If the light is burned out, you would not be aware that one or more systems on your car are not operating properly. If the CEL is burned out, have it replaced.

If you have the car’s OBD system scanned for trouble codes, that will give you indications of what systems on your car are not working as they should. Whether the CEL is burned out or not, it is possible that the OBD system has stored trouble codes. It is very possible that rectifying the problems leading to OBD trouble codes will cause the VSC light to go out.

Check the CEL and have the OBD system scanned for trouble codes, and then come back to this thread to report your findings on both issues.

The CEL does come on. I had the car tested and the scan code was P0420. sys eff below threshold (bank 1). .5 needs SOP CAT That is what the Toyota dealer gave me. So, I took it to a Lexus dealer and they said it was only a gas cap. Natually I replaced the cap as opposed the converter.It still comes on periodically. Actually there are 2 lights that come on. One says "V"SC the other “VSD OFF”.

Well, as I said, on many cars an illuminated CEL will also trigger the VSC warning light. Have the repairs done that are indicated by the stored trouble codes (in this case, possibly replacing the Cat) and the VSC light should go off.

Incidentally, if your state has an emissions test as part of the state inspection, you will not be able to pass your state inspection with a bad catalytic converter or any other situation that triggers the CEL.

When the VSC lights come on, it does not trigger the CEL. I know the CEL works only because it comes on prior to starting. If I take my car back to the dealer without the CEL light on and have it scanned, will they get an error code?

Maybe yes, maybe no.

Instead of the dealership, take the car to an auto parts retailer such as Auto Zone, Advance Auto, O’Reilly Auto, Napa, etc. Many of them will do the scan without charge. Get the code(s) and then come back here to report yor findings.

OK: This time when the VSC lights came on the Check engine light came on also. And now stays on even when I restart the car. I went to NAPA used their scanner (for free) Thanks; and got the Code PO420. The same code I got before Lexus changed out the gas cap. The gas cap “fix” worked for 6 months??? If it was chump change to replace the cat I do it, but I would like to know that my $1500 is going to give me a perm fix.
I apprecieate your thoughts.

I have had a problem with my VSC lights coming on ever since I purchased my 1999 ES300 new. While it was still under warranty, I took it to the dealer on 4 separate occassions. At that time both the VSC and VSC OFF lights were coming on. The CEL light never came on. The lights would always turn off when I shut the car off. The two VSC lights only came on sproadically and would not leave a saved code in the computer so the Lexus dealer had a very difficult time diagnosing the problem. They replaced the Mass Airflow Meter twice. After doing so, the lights would stay off for a few weeks or even months, but would starting acting the same way again eventually. When the car ran out of warranty, they started coming on more frequently. I finally took it into another Lexus dealer who drove the car 50+ miles to finally get the code to come on so they could capture it on their code reader. They determined it was the Yaw Rate Sensor in the VSC system and replaced it for about $800. I crabbed at them enough about the fact I took the car in several times under warranty for the problem, so Lexus paid for the part which brought the cost of repair down to about $350 for labor.

Now, in the past couple of months, my VSC, VSC OFF, and CEL lights are all coming on and staying on even after I shut the car off and turn it on again. I too, am getting the P0420 code on the OBD2 reader. The repair software is saying the catalytic converter is the most likely cause and the secondary cause could be the Air/Fuel ratio sensor. It looks like you can buy a catalytic converter and do the repairs pretty easily yourself for around $250 if you don’t need the CA compliant converter.