Start with the C1202. See if you can resolve this first.

 

Sensor(s)

 

Gas cap

 

I bought my 2001 XLS from my friend for $300 because I don’t know what years but the 2001 particular has a flaw in the ABS computer. Those are very easy to R&R it’s the part that’s expensive. We tried to get ones from the junkyard, but like I said there’s a flaw in the original computer so you have to go to Toyota like I did get it. Replaced the revised one I have an XLS Toyota ordered one for an LS. I got lucky because they had to keep my car longer and instead of costing me $1100 and only caused me $700. Hence, why my friend sold it to me for cheap. I drove around for a number of months before it went out on me and The the VSC light comes on when pretty much anything is wrong with your Avalon! I have replaced the O2 sensors the timing belt thermostat water pump thermostat harness alternator battery shocks struts, bushings at the bottom of the steering rack, bushings at the rear control arms, plugs, and coil packs tires, yeah pretty much rebuilt her she has over 325,000 miles on it and I believe keeping up with the timing belt. This car will run forever to the point, if your VSC light is on and your brake light is on then I can almost 100% tell you it’s the ABS computer and it’s going to go out on you when it goes out you will know cause everything will lock up so you’re gonna need to go through Toyota and get the part through them it literally takes minutes for them to R&R. The part itself is just expensive they have to reset it but like I said, your VSC is going to go off and the lady is going to come on pretty much over anything wrong with your vehicle all that stuff that I’ve replaced on it the VSC light was on every time which means my vehicle suspension control was turned off along with the engine light they do that so you get it fixed, good luck and I know that’s what was wrong with your car. I’m willing to bet it is.