DTC 0412

Front Heated Oxygen Sensors (P0134: Right Bank) (P0154: Left Bank)









COMPONENT DESCRIPTION
The front heated oxygen sensor is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The front heated oxygen sensor has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The front heated oxygen sensor signal is sent to the ECM. The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.






CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.






ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values, and are measured between each terminal and (25) (ECCS ground).









ON BOARD DIAGNOSIS LOGIC
To judge the malfunction, the diagnosis checks that the front heated oxygen sensor output is not inordinately high.


DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.


With Generic Scan Tool
(1) Turn ignition switch "ON" and wait at least 5 seconds.
(2) Select "MODE 3" with GST.






Electrical Diagrams/Left Bank






Circuit Connectors/Left Bank






Electrical Diagrams/Right Bank






Circuit Connectors/Right Bank






DIAGNOSTIC PROCEDURE


COMPONENT INSPECTION
Front heated oxygen sensor






Without Scan Tools
(1) Start engine and warm it up to normal operating temperature.
(2) Set voltmeter probes between ECM terminal (50) RH, (51) LH (sensor signal) and (25) (ECM ground).
(3) Check the following with engine speed held at 2,000 rpm constant under no load.
- Malfunction indicator lamp goes on more than 5 times within 10 seconds in Diagnostic Test Mode II (FRONT HEATED OXYGEN SENSOR MONITOR).
- The maximum voltage is over 0.6V at least one time.
- The minimum voltage is below 0.35V at least one time.
- The voltage never exceeds 1.0V.