P0155

SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the front heated oxygen sensor heaters corresponding to the engine speed.

OPERATION
Engine speed rpm Front heated oxygen sensor heaters
Above 3,600 OFF
Below 3,600 ON

CONSULT-II Reference Value in Data Monitor Mode
Specification data are reference values.

On Board Diagnosis Logic
Malfunction is detected when the current amperage in the front heated oxygen sensor heater circuit is out of the normal range. (An improper voltage drop signal is sent to ECM through the front heated oxygen sensor heater.)

Possible Cause
- Harness or connectors
(The front heated oxygen sensor heater circuit is open or shorted. )
- Front heated oxygen sensor heater

DTC Confirmation Procedure

NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is between 10.5 V and 16 V at idle.

WITH CONSULT-II
1. Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT.
2. Start engine and run it for at least 6 seconds at idle speed.
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

WITH GST
1. Start engine and run it for at least 6 seconds at idle speed.
2. Turn ignition switch "OFF" and wait at least 10 seconds.
3. Start engine and run it for at least 6 seconds at idle speed.
4. Select "MODE 3" with GST.
5. If DTC is detected, go to "Diagnostic Procedure" below.
- When using GST, "DTC Confirmation Procedure" should be performed twice as much as when using CONSULT-II because GST cannot display MODE 7 (1st trip DTC) concerning this diagnosis. Therefore, using CONSULT-II is recommended.

Wiring Diagram