Troubleshooting
DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2)CIRCUIT DESCRIPTION
DTC Detecting Condition:
The heated oxygen sensor is used to monitor oxygen concentration in the exhaust gas. 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 in the vicinity of 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 farther away from the engine assembly.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The heated oxygen sensor generates waveform of a voltage between 0 V and 1 V in response to the oxygen concentration in the exhaust gas. When the output voltage of the heated oxygen sensor is 0.5 V or more, the ECM judges that the air-fuel ratio is RICH. When it is 0.4 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 a malfunction in the rear heated oxygen sensor and sets a DTC. Also, if the rear heated oxygen sensor output remains at less than 0.05 V for more than 114 sec. when ECM monitored the heated oxygen sensor for 190 sec. while the air-fuel feed back is being performed (The detecting condition differs depending on the type of vehicles), the ECM will interpret this as a fault. In either case, the ECM will turn on the MIL and set a DTC.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
a. Connect the hand-held tester to the DLC3.
b. Switch the hand-held tester from the Normal Mode to the Check (Test) Mode.
c. Start the engine and let the engine idle for 60 seconds or more.
d. Drive the vehicle at 40 km/h (25 mph) or more for 40 seconds or more.
e. Let the engine idle for 10 seconds or more.
f. Preform steps (d) to (e) 11 times.
HINT:
- During performing the steps (d) to (e) 11 times, drive the vehicle at over 65 km (40 mile) and make the fuel cut happen for over 3 sec.
- If a malfunction exists, the MIL will be indicated on the multi information display during step (f).
NOTE: If the conditions in this test are not strictly followed, detection of the malfunction will not be possible. If you do not have a hand-held tester, turn the ignition switch OFF after performing steps (c) to (f), then perform steps (c) to (f) again.
Step 1:
Step 2 - 3:
Step 4 - 5:
Step 6 - 7:
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
Narrowing down the trouble area is possible by performing "A/F CONTROL" ACTIVE TEST (heated oxygen sensor or other trouble areas can be distinguished).
Perform ACTIVE TEST using hand-held tester (A/F CONTROL).
HINT: "A/F CONTROL" is the ACTIVE TEST which changes the injection volume to -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 speed at 2,500 rpm for approximately 90 seconds.
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 of 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, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.
CHECK FOR INTERMITTENT PROBLEMS
Hand held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with hand held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.
a. Clear the DTCs. (See step 2)
b. Set the check mode. (See step 3)
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.