Rear Heated Oxygen Sensor Heater

SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the rear heated oxygen sensor heater corresponding to the engine conditions.

Engine speed (rpm) / Rear heated oxygen sensor heater
Above 3,200 / OFF
Below 3,200 / ON




CONSULT REFERENCE VALUE IN DATA MONITOR MODE




ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values and are measured between each terminal and (43) (ECCS ground).




ON BOARD DIAGNOSIS LOGIC

DIAGNOSTIC TROUBLE CODE DETECTING CONDITION
With Consult
(1) Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT.
(2) Start engine and run it at least 5 seconds at idle speed.

OR

With GST
(1) Start engine and run it at least 5 seconds at idle speed.
(2) Turn ignition switch "OFF" and wait at least 5 seconds.
(3) Start engine and run it at least 5 seconds at idle speed.
(4) Select "MODE 3" with GST.

OR

No Tools
(1) Start engine and run it at least 5 seconds at idle speed.
(2) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(3) Perform "Diagnostic Test Mode II" (Self-diagnostic results) with ECM.
- When using GST, "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" should be performed twice as much as when using CONSULT or ECM (Diagnostic Test Mode II) because GST cannot display MODE 7 (1st trip DTC) concerning this diagnosis. Therefore, using CONSULT or ECM (Diagnostic Test Mode II) is recommended.




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION

Rear heated oxygen sensor heater
Check the following.




1. Check resistance between terminals (1) and (4).

Resistance: 3.0 - 4.0 Ohms at 25°C (77°F)

2. Check continuity.

Terminal No. / Continuity
(2) and (1), (3), (4) / No
(3) and (1), (2), (4) / No

If NG, replace the rear heated oxygen sensor.

CAUTION: Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.