Circuit Description
WARNING: This page is about a different car, the 2003 Toyota Camry. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
- Detecting condition for DTC P0031 is when heater current is 3.0 A or less when the heater operates (1 trip detection logic).
- Detecting condition for DTC P0032 is when heater current exceeds 19.7 A when the heater operates (1 trip detection logic).
For circuit description, refer to DTC P2195: OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK NO. 1 SENSOR NO. 1) & DTC P2196: OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK NO. 1 SENSOR NO. 1) .
The engine control module (ECM) provides a pulse width modulated control circuit to adjust current through the heater. The A/F sensor heater circuit uses a relay on the B+ side of the circuit. See Fig 1.