P1144

P1144 HO2S1







Component Description
The heated oxygen sensor 1 is placed into the front tube. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions. The heated oxygen sensor 1 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 1 V to 0 V.

Consult-II Reference Value In Data Monitor:

ECM Terminals And Reference Value:

On Board Diagnosis Logic
To judge the malfunction, the output from the heated oxygen sensor 1 is monitored to determine whether the "rich" output is sufficiently high. The "lean" output is sufficiently low. When both the outputs are shifting to the rich side, the malfunction will be detected.

Malfunction is detected when the maximum and minimum voltages from the sensor are beyond the specified voltages.

POSSIBLE CAUSE
- Heated oxygen sensor 1
- Fuel pressure
- Injectors
- Heated oxygen sensor 1 heater

With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine and wait at least 5 seconds.
3. Turn ignition switch ON and select "HO2S(1) (B1)/(B2) P1144/ P1164" of "HO2S(1)" in "DTC WORK SUPPORT" mode with CONSULT-II.
4. Touch "START".
5. Start engine and let it idle for at least 3.5 minutes.

NOTE: Never raise engine speed above 3,200 rpm after this step. If the engine speed limit is exceeded, return to step 5.













6. When the above conditions are met, "TESTING" will be displayed on the CONSULT-II screen. Maintain the conditions continuously until "TESTING" changes to "COMPLETED". (It will take approximately 50 seconds or more.)
If "TESTING" is not displayed after 5 minutes, retry from step 2.

7. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS". If "NG" is displayed, refer to "Diagnostic Procedure" below.




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

Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 50 (bank 1 signal) or 51 (bank 2 signal) and engine ground.
3. Check one of the following with engine speed held at 2,000 rpm constant under no load.

- The maximum voltage is below 0.8 V at least one time.
- The minimum voltage is below 0.35 V at least one time.

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

Diagnostic Procedure

Step 1 - 2:

Step 3 - 4:

Step 5:

Step 6:

Step 7 - 8:

Step 9 - 10: