The service light will need to be reset on the back of the instrument cluster. Alternately, and it's not a bad solution, take the bulb holder out. The thing is useless anyway, just a 5000 mile clock that sets it off.

The check engine light indicates something more serious and is a useful diagnostic tool. The info is the same for similar era 740 models, so see the FAQ.

BTW a car built in August or later falls into the next model year. Yours is a late 1989. To verify, see the VIN number. The 10th digit is K for 1989, L for 1990. Both of your cars will have Bosch LH-Jetronic 2.4 injection, sometimes called LH-Jet or just LH 2.4.
With fuel injection troubles in any 1989, it's useful to know that the original computers used were a failure item. Your engine computer is located under the dashboard, on the right side wall of the car near the front door hinges. The troublesome computers have a long Bosch part number ending in "561". The replacement "951" model was fitted to later years and corrects the failures. Any computer with a "REMAN" sticker indicates a Bosch repaired unit that also would be fine.
Good luck with your cars.
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '89 244DL/AW70- 212K Not too distant past: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K