P0146

DTC P0146: Heated Oxygen Sensor Circuit No Activity Detected (bank 1, sensor 3) [California]

Center Exhaust Pipe Heated Oxygen Sensor Circuit:

CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 101) from the output terminal (terminal No. 3) of the center exhaust pipe heated oxygen sensor.
- Terminal No. 4 of the center exhaust pipe heated oxygen sensor is grounded with ECM (terminal No. 116).
- The ECM applies an offset voltage of 0.5 volt to terminal No. 4 of the center exhaust pipe heated oxygen sensor.

TECHNICAL DESCRIPTION
The ECM checks for the center exhaust pipe heated oxygen sensor output voltage.

DESCRIPTIONS OF MONITOR METHODS
Center exhaust pipe heated oxygen sensor output voltage does not change during specified.

MONITOR EXECUTION
Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Heated oxygen sensor (front) monitor
- Heated oxygen sensor (front) heater monitor
- Heated oxygen sensor (front) inactive monitor
- Heated oxygen sensor offset voltage monitor
- Air/fuel ratio feedback monitor
- Center exhaust pipe heated oxygen sensor heater monitor

Sensor (The sensor below is determined to be normal)
- Mass airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor

DTC SET CONDITIONS

Logic Flow Chart:

Check Conditions
- Engine coolant temperature is higher than 76 °C (169 °F).
- The heated oxygen sensor (front) is active.
- The cumulative mass airflow sensor output is higher than 2,900 g.
- Repeat 3 or more times: drive*1,Stop*2

Drive*1:
- Engine speed is higher than 1,500 r/min.
- Volumetric efficiency is higher than 40 percent.
- Vehicle speed is higher than 30 km/h (19 mph).
- A total of more than 10 seconds have elapsed with the above mentioned conditions, and more than 2 seconds have elapsed with the fuel shut off.

Stop*2:
- Vehicle speed is lower than 1.5 km/h (1.0 mph).

Judgement Criterion
- Change in the output voltage of the center exhaust pipe heated oxygen sensor is lower than 0.313 volt.

NOTE: Monitoring stops after fuel has been shut off for more than 38 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 13. OBD-II Drive Cycle

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Center exhaust pipe heated oxygen sensor failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Using scan tool MB991958, check data list item B1: Heated Oxygen Sensor Bank 1, Sensor 3 (center exhaust pipe).






CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991958 to the data reading mode for item B1, Heated Oxygen Sensor Bank 1, Sensor 3 (center exhaust pipe).
a. Transaxle: 2nd speed
b. Drive with wide open throttle
c. Engine: 3,500 r/min
- The output voltages should be between 0.6 and 1.0 volt.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points-How to Cope with Intermittent Malfunctions.

NO : Replace the center exhaust pipe heated oxygen sensor. Then go to Step 2.

STEP 2. Test the OBD-II drive cycle.

1. Replace the center exhaust pipe heated oxygen sensor. When the center exhaust pipe heated oxygen sensor is replaced, carry out a test drive with the drive cycle pattern. Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 13. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0146 set?

YES : Refer to MFI P0143-Heated Oxygen Sensor Circuit Low Voltage (bank 1, sensor 3), P0143 DTC P0144-Heated Oxygen Sensor Circuit High Voltage (bank 1, sensor 3). P0144

NO : The inspection is complete.