DTC P0137 HEATED OXYGEN SENSOR 2 (REAR) (LOW VOLTAGE); Component Description; CONSULT-II Reference Value; On Board Diagnosis Logic
EF & EC-7134spec tableSEF622X throttle-opener figure included but no narrative tie-in on this page — likely linked to fuel-cut conditions referenced in OBD logic.
CG10, CGA3
Component Description
The heated oxygen sensor 2 (rear), after three way catalyst, monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the heated oxygen sensor 1 (front) are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions.
CONSULT-II Reference Value in Data Monitor Mode
Specification data are reference values.
CONSULT-II Data Monitor — HO2S2
HO2S2 (B1)
CONDITIONEngine: After warming up — Revving engine from idle to 3,000 rpm
SPECIFICATION0 - 0.3V ↔ Approx. 0.6 - 1.0V
HO2S2 MNTR (B1)
CONDITIONEngine: After warming up — Revving engine from idle to 3,000 rpm
SPECIFICATIONLEAN ↔ RICH
On Board Diagnosis Logic
The heated oxygen sensor 2 (rear) has a much longer switching time between rich and lean than the heated oxygen sensor 1 (front). The oxygen storage capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2 (rear), ECM monitors whether the output voltage of the sensor is sufficiently low during various driving conditions such as fuel-cut.