P0136
DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2)CIRCUIT DESCRIPTION
DTC Detection Condition:
The front oxygen sensor is used to monitor oxygen concentration in the exhaust. For optimum catalytic converter operation, the air fuel mixture must be maintained near the ideal "stoichiometric" ratio. The heated oxygen sensor output voltage changes suddenly at the stoichiometric ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust gas increases. And the heated oxygen sensor informs the ECM of the LEAN condition (low voltage, i.e. less than 0.45 V). When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio, the oxygen will be vanished from the exhaust gas. And the heated oxygen sensor informs the ECM of the RICH condition (high voltage, i.e. more than 0.45 V).
HINT: Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions Part 1:
Typical Enabling Conditions Part 2:
Typical Malfunction Thresholds:
Component Operating Range:
Monitor Result (MODE 06 DATA):
The heated oxygen sensor generates waveform of a voltage between 0 V and 1 V in response to the oxygen concentration in the exhaust gases. When the output voltage of the heated oxygen sensor is 0.55 V or more, the ECM judges that the air-fuel ratio is RICH. When it is 0.40 V or less, the ECM judges that the air-fuel ratio is LEAN.
If the rear heated oxygen sensor output does not change between RICH and LEAN during "Stop and GO" driving, the ECM interprets this as malfunction in the sensor and sets a DTC. Also, if the sensor output remains at less than 0.05 V for more than 126 seconds (when ECM monitored the sensor for 210 seconds while the air-fuel feed back is being performed), the ECM will interpret this as a fault. In either case, the ECM will turn on the MIL and set a DTC.
Wiring Diagram:
Step 1 - 3:
Step 4 - 5:
Step (5 Continued - 7):
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
Narrowing down the trouble area is possible by performing the "SENSOR 1 (FRONT SENSOR)" ACTIVE TEST (heated oxygen sensor or other trouble areas can be distinguished).
a. Perform ACTIVE TEST using the hand-held tester (A/F CONTROL).
HINT: "A/F CONTROL" is ACTIVE TEST which changes the injection volume -12.5% or +25%.
1. Connect the hand-held tester to the DLC3 on the vehicle.
2. Turn the ignition switch ON.
3. Warm up the engine by running the engine at 2,500 rpm for approximately 3 minutes.
4. Select the item "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL".
5. Perform "A/F CONTROL" with the engine in an idle condition (press the right or left button).
Result:
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:
+25% -> rich output: More than 0.5 V
-12.5% -> lean output: Less than 0.4 V
NOTE: There is a delay of few seconds in the sensor 1 (front sensor) output, and there is about 20 seconds delay at maximum in the sensor 2 (rear sensor).
The following A/F CONTROL procedure enables the technician to check and graph the voltage outputs of both the heated oxygen sensors.
For displaying the graph indication, enter "ACTIVE TEST / A/F CONTROL / USER DATA", then select "O2S B1S1 and O2S B1S2" by pressing "YES" button and push "ENTER" button before pressing "F4" button.
HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may be open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
CHECK FOR INTERMITTENT PROBLEMS
Hand-held tester only:
By putting the vehicle's ECM in the check mode, the 1 trip detection logic is possible instead of the 2 trip detection logic, and the sensitivity to detect faults is increased. This makes it easier to detect intermittent problems.
a. Clear the DTCs.
b. Set the check mode.
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.