P0159

DTC P0159: Cylinder 2, 3 Heated Oxygen Sensor (Rear) Circuit Slow Response

Cylinder 2, 3 Heated Oxygen Sensor (Rear) Circuit (Part 1):

Cylinder 2, 3 Heated Oxygen Sensor (Rear) Circuit (Part 2):

CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM [M/T] or the PCM [A/T] (terminal No. 96) from the output terminal (terminal No. 4) of the cylinder 2, 3 heated oxygen sensor (rear).
- Terminal No. 2 of the cylinder 2, 3 heated oxygen sensor (rear) is grounded with ECM [M/T] or PCM [A/T] (terminal No. 105).
- The ECM [M/T] or the PCM [A/T] applies an offset voltage of 0.5 volt to terminal No. 2 of the cylinder 1, 4 heated oxygen sensor (rear)

TECHNICAL DESCRIPTION
- The output signal of the cylinder 2, 3 heated oxygen sensor (front) is compensated by the output signal of the cylinder 2, 3 heated oxygen sensor (rear).
- The ECM [M/T] or the PCM [A/T] checks for the cylinder 2, 3 heated oxygen sensor (rear) output voltage.

DESCRIPTIONS OF MONITOR METHODS
Cylinder 2, 3 heated oxygen sensor (rear) output voltage does not reach 0.2 volt after fuel cut operation.

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
- Heated oxygen sensor heater (rear) monitor
- 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:

Check Conditions
- Engine coolant temperature is higher than 76 °C (169 °F).
- The cylinder 2, 3 heated oxygen sensor (front) is active.
- The cumulative mass airflow sensor output is higher than 1,638 g.
- Fuel is being shut off.
- Cylinder 2, 3 heated oxygen sensor (rear) output voltage is higher than 0.5 volt when fuel cut is started.
- It has been taking more than 180 seconds since the drive signal of the cylinder 2, 3 heated oxygen sensor (rear) heater was turned on.
- Barometric pressure is higher than 76 kPa (22.4 in.Hg).

Judgement Criterion
- Cylinder 2, 3 heated oxygen sensor (rear) output voltage does not reach 0.2 for 6 seconds.

Check Conditions
- Engine coolant temperature is higher than 76 °C (169 °F).
- The cylinder 2, 3 heated oxygen sensor (front) is active.
- The cumulative mass airflow sensor output is higher than 1,638 g.
- Cylinder 2, 3 heated oxygen sensor (rear) output voltage is higher than 0.5 volt when fuel cut is started.
- It has been taking more than 180 seconds since the drive signal of the cylinder 2, 3 heated oxygen sensor (rear) heater was turned on.
- Barometric pressure is higher than 76 kPa (22.4 in.Hg).
- The ECM [M/T] or the PCM [A/T] monitors for this condition for 3 cycles of 0.5 seconds each during drive cycles.

Judgement Criteria
- Cylinder 2, 3 heated oxygen sensor (rear) output voltage does not reach 0.2 volt for 1 second from 0.4 volt.
- The ECM [M/T] or the PCM [A/T] monitors for this condition once during the drive cycle.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 11. OBD-II Drive Cycle

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Cylinder 2, 3 heated oxygen sensor (rear) deteriorated.
- Connector damage.
- ECM failed. [M/T]
- PCM failed. [A/T]

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 AF: Cylinder 2, 3 Heated Oxygen Sensor (rear).







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 AF, Cylinder 2, 3 Heated Oxygen Sensor (rear).
4. Warm up the engine.
- After increasing the output voltage 0.5 volt or more by the engine revving, finish it. Then confirm that the output voltage reduces to 0.2 volt or less within 6 seconds.

5. 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 : Replace the heated oxygen sensor (rear). Then go to Step 2.

STEP 2. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 11. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0159 set?

YES : Refer to DTC P0157 - Cylinder 2, 3 Heated Oxygen Sensor (rear) Circuit Low Voltage, P0157 DTC P0158 - Cylinder 2, 3 Heated Oxygen Sensor (rear) Circuit High Voltage. P0158

NO : The inspection is complete.