Upstream O2 sensor monitor: Description: Notes
The upstream sensor will cause an emission increase when its response time increases too much (A/F Loop period or frequency check).
The period of the A/F loop is measured and the number of lean/rich transitions are counted. The sum of valid periods is then calculated.
The corresponding limit period versus operating point is acquired.
A failure is detected when the sum of the measured periods exceeds the sum of the corresponding limit.
Description of the strategy
O2 sensor monitoring is a sequential diagnosis made during steady state conditions.
The diagnosis is composed of two main phases:
- Measurement
- Diagnosis