I have an /05 Highlander. A new short block was installed @ 74,000 mi. A week later my VSC light came on. The dealer replaced the O2 sensor & light went out..for 4 miles. Now both the eng. & VSC lights are on. Took it back & dealer & replaced O2 sensor for the second time. Was told the second O2 sensor was defective ?? Light was out for 7 miles this time. Took it back & this time the dealer replaced the TPS. But that wasn't it because when I went ti pick it up both lights are still on. Now they tell me the EGR valve needs replaced & ordered one ??? Pls help

That means Vehicle Stability Control, VSC. It has something to do with your cars stability program. VSC is the system that would help you safely out of a slippery hill in snow and ice. It tries it’s best to keep you going straight down the road. Also known as traction control. Could just be a stored fault code that randomly years later popped up again. Does the VSC still work? You can clear the code by unplugging your battery for 20 minutes. See if the light comes back on. If it does, check the wiring and connections to the wheel and tire speed sensors and make sure they’re not damaged. Also, check the VSC module, which is located with the fuse box, most likely under the hood of the car on the drivers side. Usually it’s just those and you can buy a new module and install it in all of 5 seconds. If you’re able to, do a little inspecting underneath where the rear wheel speed sensor cables are connected. Make sure there’s no damage to the wiring and also where it connects. A wheel sensor could get damaged. It’s not uncommon, especially if you live in cities like Boston or New York City, there are gargantuas potholes everywhere that destroy car wheels and tires and suspension sometimes too. Not sure year and other stats, but hope this helps man!

you need a new vvti sensor. happen to me on my gs430 and my rx300. one will go bad then 6 months later the other will. easy to replace its just one 10mm bolt and a plug.

A p0420 sets after Engine and catalyst are warmed up, vehicle driven within set vehicle engine speed range and waveforms of heated O2 sensors bank 1 sensor 1 and bank 1 sensor 2 have the same amplitude.
Catalytic convertor and O2 sensors need to be tested

Had this happen to my '05 Vibe (Matrix evil clone) recently. Mechanic read & reset codes. The non-flashing Engine light showed 2 large emission leaks. The VSC could be any number of things. He said hopefully it was a false positive on the VSC... potentially expensive to fix. Lights stayed off for a couple weeks & are now back on. I'm planning on seeing him later today. Also, said stability light stayed off, it is still working. fwiw...

your O2 sensor heater circuit is not working. Can be caused by wiring, including connector, or sensor. Check connector. If good, it's probably the sensor. You can troubleshoot the sensor if you have an ohmmeter. If you want to do this, please get back to me and I'll send instructions.
The sensor is screwed into the exhaust manifold on the front of the engine.

2000 toyota highlander just had oil changed and VSC lightis on.
what to do

You have to use a scanner and pull the code out that is causing the check engine light to come on. whatever code/codes you find are probably related to vsc light.
Good luck and keep me posted

no such thing as a catalytic computer... there is a catalytic converter ... part of the exhaust system so they may now be "guessing" that it's an O2 sensor. take the car to autozone... they will scan the codes for free.... post the codes here tho the lads and lasses there are pretty clever and will probably tell you what the codes mean.