First, do you know which codes set off the check engine light?
If you haven't checked your codes, here's how you do it.
You have an LED display unit in your engine compartment, on the passenger side near the firewall. Press the button for 3 seconds (with the engine off and the ignition in the on position) and release. Count the number of flashes for the fault code. One blink indicates no codes present. Repeat the code retrieval by again depressing the button and count the blinks a second time. If you get the same number then there is only one code. If you get a different number of flashes, then you have more than one code. Keep repeating till all codes are read. This is indicated by the repeat of the first code received.
To clear the codes and reset the check engine light, after you've checked the codes, wait at least two seconds, then you hold the button down for six seconds. Each code must be erased individually (if you have more than one).
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".