P1166

P1166 HO2S2




Component Description
The heated oxygen sensor 2, after three way catalyst, monitors the oxygen level in the exhaust gas on each bank.

Even if switching characteristics of the heated oxygen sensor 1 are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2.

This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions.

Under normal conditions the heated oxygen sensor 2 is not used for engine control operation.

Consult-II Reference Value In Data Monitor:

ECM Terminals And Reference Value:

On Board Diagnosis Logic
The heated oxygen sensor 2 has a much longer switching time between rich and lean than the heated oxygen sensor 1. The oxygen storage capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel-cut.

Malfunction is detected when the minimum voltage from the sensor is not reached to the specified voltage.

POSSIBLE CAUSE
- Harness or connectors
(The sensor circuit is open or shorted.)

- Heated oxygen sensor 2
- Fuel pressure
- Injectors

DTC 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.

TESTING CONDITION:
Open engine hood before conducting following procedure With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 5 seconds.
3. Turn ignition switch ON.
4. Select "DATA MONITOR" mode with CONSULT-II.
5. Make sure that "COOLANT TEMP/S" is more than 70 °C (158 °F).




6. Select "HO2S(2) (B1)/(B2) P1146/P1166" of "HO2S(2)" in DTC WORK SUPPORT" mode with CONSULT.
7. Start engine and follow the instructions of CONSULT-II.







8. Make sure that "OK" is displayed after touching "SELF_DIAG RESULTS".

If NG is displayed, refer to "DIAGNOSTIC PROCEDURE".

If "CAN NOT BE DIAGNOSED" is displayed, perform the following.

a. Stop engine and cool down "COOLANT TEMP/SE" to less than 70 °C (158 °F).
b. Turn ignition switch ON.
c. Select "DATA MONITOR" mode with CONSULT-II.
d. Start engine.
e. Perform from step 6) again when the "COOLANT TEMP/S" reaches to 70 °C (158 °F)




Overall Function Check
Use this procedure to check the overall function of the heated oxygen sensor 2 circuit. During this check, a 1st trip DTC might not be confirmed.

CAUTION: Always drive vehicle at a safe speed.

Without CONSULT-II
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminal 56 (bank 1 signal) or 57 (bank 2 signal) and engine ground.
4. Check the voltage when racing up to 4,000 rpm under no load at least 10 times.
(depress and release accelerator pedal as soon as possible)

The voltage should be below 0.48 V at least once during this procedure.

If the voltage can be confirmed in step 4, step 5 is not necessary.

5. Keep vehicle at idling for 10 minutes, then check the voltage. Or check the voltage when coasting from 80 km/h (50 MPH) in 3rd gear position (M/T), "D" position with "O/D" OFF (A/T).
The voltage should be below 0.48 V at least once during this procedure.

6. If NG, go to "Diagnostic Procedure" below.

EC-O2S2B1-01:

EC-O2S1B2-01:

Wiring Diagram

Diagnostic Procedure

Step 1 - 2:

Step 3:

Step 4 - 6:

Step 7 - 8:

Step 9 - 10: