P0146
DTC P0146: Heated Oxygen Sensor Circuit Slow Response (bank 1, sensor 3)Center Exhaust Pipe Heated Oxygen Sensor Circuit Part 1:
Center Exhaust Pipe Heated Oxygen Sensor Circuit Part 2:
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. 106).
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 heater (front) monitor
Center exhaust pipe heated oxygen sensor
Air/fuel ratio feedback 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:
Logic Flow Chart
Check Conditions
Engine coolant temperature is higher than 76 °C (169 °F).
The center exhaust pipe 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 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 AD: 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.
NO: 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 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, P0143 - Heated Oxygen Sensor Circuit Low Voltage (bank 1, sensor 3), DTC P0144 - Heated Oxygen Sensor Circuit High Voltage (bank 1, sensor 3).
NO: The inspection is complete.