help reset o2 sensor light 86 2.3-16
 

have 86 190e 2.3-16,just got the car and let a friend drive the car and he started off twice in 3rd gear thinking he was in 1st,the car of course stalled at that point.the last time the o2 sensor light came on.i took it to the dealer they said the the sensor needed to be replaced,they ordered the sensor and installed it and it shows it working fine,but the light will not go off. they cleaned all the grounds on the car,the light will go out after they put the tester on the car but when they spin the front wheel the light comes on.when i went to leave i started the car and let it run for about 3min. no light on, pulled out and when i got to about 5mph light came on. is there a reset button? HELP thanks

ttt