What does the maintenance code "500" mean on my 1999 ml 320?
Had to replace gas cap with a generic replacement. I feel that is the reason
the "check engine" light goes on. Now, maintenance code "500" lights up.
Generic caps usually don't seal properly and will cause Evap codes . Try a speed cap .they are quick fill ( no need to take off to put fuel in ) so far in haven't had any complaints or codes to clear from customers .Good luck
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