DTC 61

CIRCUIT DESCRIPTION
If a Code 61 is stored in memory the Electronic Control Module (ECM) has determined the Oxygen (O2) sensor is contaminated or degraded, because the voltage change time is slow or sluggish.

TEST DESCRIPTION
The ECM performs the oxygen sensor response time test when:
^ The Coolant temperature is greater than (85° C).
^ The Manifold Air Temperature (MAT) temperature is greater than (10° C).
^ In closed loop.
^ In decel fuel cut-off mode.

If a Code 61 is stored the oxygen sensor should be replaced.
A contaminated sensor can be caused by fuel additives, such as silicon, or by use of non approved lubricants or sealants. silicon contamination is usually indicated by a white powdery substance on the sensor fins.