| DTC Code | DTC Name |
|---|---|
| P0136 | Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) |
| P0140 | Heated Oxygen Sensor Circuit No Activity Detected (Bank 1 Sensor 2) |
DESCRIPTION
In order to obtain a high purification rate for the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel ratio. The No. 2 heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and provide the ECM with feedback to control the air fuel ratio. When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas increases. The No. 2 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 level, the oxygen concentration in the exhaust gas is reduced, and the No. 2 heated oxygen sensor informs the ECM of the rich condition (high voltage, i.e. more than 0.45 V). The ECM judges, using the voltage output of the No. 2 heated oxygen sensor, whether the air fuel ratio is rich or lean and controls the injection time accordingly. If a malfunction of the No. 2 heated oxygen sensor causes an output of abnormal voltage, the ECM is unable to perform accurate air fuel ratio control. The No. 2 heated oxygen sensor includes 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), a current flows to the heater in order to heat the sensor for accurate oxygen concentration detection.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0136 | No. 2 heated oxygen sensor output voltage is less than 0.06 V within 1 second after engine was started with engine coolant temperature less than 40°C (104°F) or less (last engine operation was stopped after warm-up). (3 trip detection logic) |
|
| P0140 | No. 2 heated oxygen sensor voltage is between 0.4 V and 0.52 V continuously for 600 seconds (3 trip detection logic) |
|
| P0140 | ECM determines that internal resistance of No. 2 heated oxygen sensor is more than 40 kΩ after warm-up (3 trip detection logic) |
|
The internal resistance of the No. 2 heated oxygen sensor cannot be measured using the tester.
CONFIRMATION DRIVING PATTERN
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
DTC P0136 is detected when the vehicle is driven at a vehicle speed of 70 to 110 km/h (43 to 68 mph) with the shift lever in the 5th position for 90 seconds or more after driving with a city driving pattern at an average speed of approximately 50 km/h (31 mph) for approximately 30 minutes from cold start (engine coolant temperature when engine start is less than 40°C (104°F)).
DTC P0140 is detected when the vehicle is driven with a city driving pattern at an average vehicle speed of approximately 50 km/h (31 mph) for approximately 30 minutes.
CAUTION / NOTICE / HINT
Inspection the fuses for circuits related to this system before performing the following inspection procedure.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, 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.
PROCEDURE
CHECK HARNESS AND CONNECTOR (NO. 2 HEATED OXYGEN SENSOR - ECM)
Disconnect the No. 2 heated oxygen sensor connector.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
| Standard Resistance | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
REPLACE NO. 2 HEATED OXYGEN SENSOR (Click here)
REPAIR OR REPLACE HARNESS OR CONNECTOR