03 SLK check engine light
 

recently checK engine light came on along with blinking gas Cap light
gas cap was not on tight , fueled up the car and put the gas cap On correctly
disconnected the battery to reset the lights.
check engine light is staying on.
is disconnecting the battery the only known way to reset that light I don't think there are any engine problems. It had a checkup two months ago no problems with anything (dealership )
any help would be appreciated and thanks in advance.****

When I recently had a P0170 code, disconnecting the battery overnight would not clear the code so I went to Autozone to have them clear it. From what I have read, the CEL for a loose gas cap should go away on its own.

Disconnecting the battery is not the way to clear the codes on that car. Drive it for a while and if the problem has been fixed, the CEL will go out on its own. If not, have the code(s) read and do a proper diagnosis.

There is a number of cycles/etc. that the OBDII system has to go through without the fault for the CEL to go out.

Or, you could just read the codes now, clear them (using a scanner) and see if the light returns. If so, you have to resolve the problem to keep the light off.

check engine light
 

the gas light did go out, check engine stayed on may be oxygen sensor didn't like loose gas cap.
I have seen scanners that come with service repair CD's and books are they worth buying?
thanks for the reply and your suggestions and comments.

My 07 ML350 did the same thing for an improperly tightened gas cap. A quick call to the dealership, and I was told it would take a few engine start/stop cycles before the CE indicator would go away. It took a couple of days before it did finally disappear.