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 P0156 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 2 SENSOR 2)
DTC P0157 OXYGEN SENSOR CIRCUIT LOW VOLTAGE (BANK 2 SENSOR 2)
DTC P0158 OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 2 SENSOR 2)
CIRCUIT DESCRIPTION
DTC Detection Condition:
The heated 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 air-fuel ratio. The heated oxygen sensor output voltage changes at the stoichiometric ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric.
If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is called LEAN. The heated oxygen sensor voltage drops below 0.45V, which informs the ECM of the LEAN condition.
If oxygen is not in the exhaust gas, the air-fuel ratio is called RICH. The heated oxygen sensor voltage increases above 0.45V, which informs the ECM of the RICH condition.
The heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), current flows to the heater in order to heat the sensor for the accurate oxygen concentration detection.
HINT:
- Bank 1 refers to the bank that includes cylinder No.1.
- Bank 2 refers to the bank that does not include cylinder No.1.
- Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The heated oxygen sensor (HO2S) outputs 0 - 1 volt of the voltage. The voltage varies with oxygen density in the exhaust gas. The ECM measures the voltage to monitor the HO2S.
Voltage
The ECM counts the time while the HO2S voltage is lower than 0.05 volts. When the time exceeds a malfunction threshold, the ECM illuminates the MIL and sets DTC P0136 or P0156 (2-trip detection logic).
Switching
The ECM counts the frequency of the HO2S switching. When the HO2S does not switch for a certain period, the ECM illuminates the MIL and sets DTC P0136 or P0156 (2-trip detection logic).
Low voltage
The ECM measures the HO2S voltage. When the voltage is lower than 0.03 volts for 90 seconds, the ECM illuminates the MIL and sets DTC P0137 or P0157.
Voltage during fuel-cut
The ECM measure the HO2S voltage during the fuel-cut. When the voltage does not reach to 0.2 volts during the fuel-cut, the ECM illuminates the MIL and sets DTC P0138 or P0158 (2-trip detection logic).
High voltage
The ECM measures the HO2S voltage. When the voltage is higher than 1.2 volts for 10 seconds, the ECM illuminates the MIL and sets DTC P0138 or P0158.
O2S TEST RESULT
Refer to "O2S TEST RESULT" for detailed information on 02S TEST RESULT. O2S Test Result
If the sensor voltage is outside the standard values, the ECM interprets this as a malfunction and sets a DTC.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
a. Connect the hand-held tester to the DLC3.
b. Switch the hand-held tester from normal mode to check mode.
c. Start the engine and warm up the engine until engine coolant temperature is more than 75 degree C.
d. Drive the vehicle at 38 mph (60 km/h) or more for 40 seconds or more.
e. Let the engine idle for 10 seconds or more.
f. Perform steps [d] and [e] 12 times.
HINT: If a malfunction exists, the MIL will be illuminated during step (f).
NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected. If you do not have the hand-held tester, turn the ignition switch to OFF after performing steps from (c) to (f), then perform steps (c) to (f) again.
Step 1-3:
Step 4-6:
Step 7-8:
Step 9:
Step 10-14:
Step 15:
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.
a. Perform the ACTIVE TEST A/F CONTROL operation.
HINT: The A/F CONTROL operation lowers the injection volume 12.5% or increases the injection volume 25%.
1. Connect the hand-held tester to the DLC3 on the vehicle.
2. Turn the ignition switch to ON.
3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
4. Select the item: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5. Perform the A/F CONTROL operation with the engine in an idle condition (press the right or left button).
Result:
A/F sensor reacts in accordance with increase and decrease of injection volume:
+25 % -> rich output: Less than 3.0 V
-12.5 % -> lean output: More than 3.35 V
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:
+25 % -> rich output: More than 0.55 V
-12.5 % --> lean output: Less than 0.4 V
NOTE: The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.
The A/F CONTROL procedure enables the technician to check and graph the voltage outputs of both the A/F sensor and the heated oxygen sensor.
To display the graph, enter ACTIVE TEST/ A/F CONTROL/USER DATA, then select "AFS B1S1 and O2S B1S2" or "AFS B2S1 and O2S B2S2" by pressing the "YES" button followed by the "ENTER" button and then the "F4" button.
HINT: Read freeze frame data using the hand-held tester or the 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.