Code 61, Degraded Oxygen (O2) Sensor
WARNING: This page is about a different car, the 1992 Pontiac Grand Prix, 1992 Oldsmobile Cutlass Supreme, and 1992 Chevrolet Lumina. However, it is still accessible from the selected car via links, so may be relevant.
If a Code 61 is stored in memory, ECM has determined O2 sensor is contaminated or degraded because voltage change time (cross counts) is slow or sluggish.
ECM performs O2 sensor response time test when coolant temperature is more than 185°F (85°C), MAT temperature is greater than 50°F (10°C), system is in "closed-loop" or in a decel fuel cut-off mode. If Code 61 is stored, O2 sensor should be replaced.