Loop status- Tech 1 dispays open or closed loop
Closed loop displayed indicates that the PCM is controlling fuel delivery according to the O2 sensor voltage. In open loop the PCM ignores the O2 sensor voltage and bases the amount of fuel to be delivered on the TP sensor, engine coolant teperature, and MAF sensor imputs only.
Closed loop operation should begin when the the O2 sensor becomes active, engine coolant temperature exceeds 50*C (122*F) for more than 30 seconds and the PCM has seen 1200 RPM or greater for 10 seconds.
At extremely high ambient temperatures or when towing a trailer it is possible for the system to remain in open loop operation to control catalyic converter temperatures