My daughter's '98 E-320 displayed a Check Engine and a Multifunction Indicator light. She took it to Autozone and they said the computer posted a P0150, P0133 and a P0155 code.
She replaced the fuel cap (the dealer charged her $41 for the thing) and the lights went out. The gasket was a bit beat up, so this was clearly the culpret.

Questions: Could the other codes for the O2 sensor and the EGR valve have been old problems that might have been fixed before she bought the car a year ago and never cleared? Or, will the trouble codes automatically erase when some time has passed?

How, exactly, do you erase fault codes. Postings mention removing the fuse for the computer, but it isn't listed as such on the fuse menu. Is disconnecting the battery the only sure way?

Many thanks for your help.

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