P0136
DTC P0136 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)DTC P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)
DTC P0138 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)
DTC P0139 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 2)
HINT: Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
DESCRIPTION
DTC Detection Condition:
The heated oxygen sensor (HO2S) is used to monitor oxygen in the exhaust gas. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S 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.
The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.
MONITOR DESCRIPTION
Monitor Strategy (Part 1):
Monitor Strategy (Part 2):
Typical Enabling Conditions:
Typical Malfunction Thresholds (Part 1):
Typical Malfunction Thresholds (Part 2):
Component Operating Range:
The ECM monitors the rear heated oxygen sensor (HO2S) in the following 4 items:
1. The HO2S voltage changes between Rich (more than 0.45 V) and Lean (less than 0.45 V) while the vehicle is running (repeating acceleration and deceleration) for 8 minutes. If not, the ECM interprets this as a malfunction, illuminates the MIL, and then sets a DTC.
2. The HO2S voltage does not remain at less than 0.05 V for a long time while the vehicle is running (60% of the time in the 220 second monitor, the sensor output is less than 0.05 V). If it does, the ECM interprets this as a malfunction, illuminates the MIL, and then sets a DTC.
3. The sensor's voltage drops to below 0.2 V (extremely Lean status) immediately when the vehicle decelerates and the fuel cut is working for 7 seconds. If not, the ECM interprets this to mean the sensor's response feature has deteriorated, illuminates the MIL, and then sets a DTC.
4. The rear oxygen sensor impedance is 5 Ohm or less, 15 kOhm or more, or output voltage is 1.2 V or more (normal voltage: 0 to 1.0 V). If so, the ECM will determine that the rear oxygen sensor or a related circuit has an open or short circuit, illuminates the MIL and sets a DTC. Impedance is detected by the IC inside the ECM.
O2S TEST RESULT
If the sensor voltage is outside the standard values, the ECM interprets this as a malfunction and sets a DTC.
CONFIRMATION DRIVING PATTERN
1. P0136:
a. Connect the intelligent tester to the DLC 3. (Procedure "A")
b. Switch the ECM from normal mode to check mode using the tester (Procedure "B").
c. Start the engine and warm it up until the engine coolant temperature reaches more than 75 degree C (167 degree F) (Procedure "C").
d. Drive the vehicle at 38 mph (60 km/h) or more for 40 seconds or more (Procedure "D").
e. Let the engine idle for 10 seconds or more (Procedure "E").
f. Perform procedure "D" or "E" 12 times (Procedure "F").
HINT: If a malfunction exists, the MIL illuminates during procedure "F".
NOTE: If the conditions in this test are not strictly followed, malfunctions may not be detected. If you do not have an intelligent tester, turn the ignition switch to OFF after performing procedure from "C" to "F", then perform steps "C" to "F" again.
2. P0137:
a. Warm up the engine and run the engine at 38 mph (60km/h) for 7 minutes.
3. P0138:
a. Warm up the engine and run the engine at idle for 30 seconds.
HINT: Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using an intelligent tester.
1. Connect an intelligent tester to the DLC3.
2. Start the engine and turn the tester ON.
3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
4. On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/ F CONTROL.
5. Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and OS2 B1S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5% or increase the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreased in the fuel injection volume.
NOTE: The A/F sensor output has a few seconds of the heated oxygen sensor output has about 20 seconds of delay at maximum.
- Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the YES button and then the ENTER button followed by the F4 button.
Wiring Diagram:
Step 1-2:
Step 3-5:
Step 5(Continued)-7:
Step 8-9:
Step 9(Continued)-12:
Step 13-15:
Step 15(Continued):
INSPECTION PROCEDURE
HINT:
- If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the intelligent tester or OBD II scan tool. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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, and other data from the time the malfunction occurred.
- If the OX1B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 will be set.