PFI Chart A-7: Left O2 Sensor Not Ready: Description
The ECM provides a .45-volt reference to oxygen sensor on circuit No. 412. When warm, a properly operating oxygen sensor will drive the reference voltage lower (below .45 volts) to indicate lean mixtures and higher (above .45 volts) to indicate a rich mixture.
NOTE:
The following step numbers refer to circled numbers on diagnostic chart. See Fig 1
. For circuit identification, see Figure
.
- At key on with oxygen sensor disconnected, parameter ED32 should read .45 volts (nominal). Lower or higher voltage indicates circuit problems.
- The ECM compares voltage on circuit No. 412 to ground voltage on circuit No. 413. It is essential that oxygen sensor ground and ECM show good continuity with no voltage difference with engine running.