I went to an auto parts store 'cause my check engine light and vsc light came on, on my 2006 Toyota Avalon-Touring. I bought a new gas cap a couple days ago. The light is still on.

that code 356 is a bad coil. if it is completely dead than you now have a 5 cylinder car.... very bad not only on mpg but also on the life of the engine. when you have a "dead hole" it can affect the other cylinders and you have misfire codes for all 6..... this could mean you simply need a tune up or that there is something affecting all cylinders. check for a vacuum leak after the air flow sensor, or a ruptured fuel pressure regulator (remove the vacuum line at the regulator and smell for gas cause there should not be gas on that side of the diaphragm) fouled spark plugs, clogged exhaust or catalytic converter, stuck open or dirty EGR valve to name a few. change that #6 coil first and at least inspect or change the spark plugs... c1201 relates to a communication stop between ECU's , don't assume that as the vsc lights etc were illuminated then that is the system that is faulty. It is most likely that the fault is within the engine system but with vehicles equipped with vsc all systems are linked so a fault with one will log a code in all others ( normally a communication stop code as you have)
I would advise fixing the engine codes first then get the other systems checked out

I had Advanced Auto check the code. While there were other potential causes, it was the Gas Cap! Replaced it and no problems since. The lights for VSC and Check Engine went off a few miles down the road

Toyota Avalon 2006 vsc, skid light and check engine light on. Codes P0031, P0038 and code ,P2238

The inspectors had to remove your fuel cap to inspect it and might have failed to put it back on tight enough. This is a common problem and will cause your "check engine light" to come on. Check the tightness of the cap and then take your car to any major auto parts store and have them read out the stored trouble code that was set when the check engine light came on. They will do this for free. Copy down the code(s) and then have them erased. This will reset the check engine light. Check the code(s) at the store to see if it corresponds to a loose fuel cap. If so, your problem is solved.

If not, you lucked out and passed your inspection just before a problem cropped up! Use the codes you copied down and get code definitions at the auto parts store. This is the place to start for diagnosing the problem.

The crankshaft sensor need to be checked.

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

Some auto parts stores (like AutoZone) will diagnose the code for the check engine light for free. If the vehicle is running fine it may be something as simple as a bad oxygen sensor.

Most major Auto Parts stores Advance/Auto Zone will get the diagnostics codes from the cars computer and tell you why the light is on and what the problem is if there is a problem.

You have an issue with the engine. The other lights come on when the Check Engine light comes on. The most common reason for the Ck Engine light on is a loose gas cap. If the cap is tight, you will need to find someone who can scan the car's ECU and give you the DTC code. Without the code, we cannot provide any more ionfor at this time.Get the code and get back to us; then we can solve the problem.

I just had the same issue. Cost me $40.00 to find out my gas cap wasnt clicked all the way. He also said that after the error arises, simply closing the gas until it clicked may not have removed the error code from the computer. Not sure how, but you might have to reset the computer, maybe just pull the battery?

Sean