P219B AIR FUEL RATIO CYLINDER IMBALANCE BANK 2

The Cylinder Imbalance Detection requires that the Upstream O2 Sensors are capable of operating at high frequencies,
since an aged O2 Sensors response capability at a higher frequency range can be degraded. Therefore, before this monitor
can become active, the O2 Sensor High Frequency Response monitor is performed to see if the sensor is even capable of
detecting an imbalance.
Once active, the Cylinder Imbalance Detection monitor matches up the Upstream O2 Sensor signal with the corresponding
cylinders on that bank. Each cylinder is monitored and adjustments are made as needed for each cylinder to correct an air/
fuel ratio imbalance. If an individual cylinder reaches a calibrated adaptation threshold (15%), the diagnostic monitor will
be considered failing.