i have a toyota rav 4 2007. check engine light VSC AND 4X4 lights came on . on 1996 Toyota RAV4

After 2 days the lights went off on their own.Since then car been fine apart from on odd occasion when going up or downhill a grey smoke comes from the exhaust.Then clears after a few seconds , no loss of power.....any ideas please for this non mechanical Englishman...thanks.

Asked by for the 1996 Toyota RAV4
have it scan tested for codes
yes i will thanks.
I had the same problem on my 2007 Rav 4. The cause was just a loose gas cap. If it isn't closed properly or the senor is broken, those 3 lights will go on. I simply opened the gas tank, took out the cap then snugly replaced and voila the lights went off. I was able to do this and I am a Chic! Easy
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have the codes checked if the engine light is out your ecm stores codes and can be found with an obd reader
thanks very much...will do