Troubleshooting
DTC P0136 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)CIRCUIT DESCRIPTION
DTC Detection Condition:
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The heated oxygen sensor (bank 1, 2 sensor 1) has the characteristic and that output voltage, which 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 increases and the heated oxygen sensor informs the ECM of the LEAN condition (small electromotive force: (< 0.45 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the exhaust gas in reduced and the heated oxygen sensor informs the ECM of the RICH condition (large electromotive force: (> 0.45 V).
The ECM judges by the electromotive force from the heated oxygen sensor whether the air-fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the heated oxygen sensor causes output of abnormal electromotive force, the ECM is unable to perform accurate air-fuel ratio control. 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 temp. of the exhaust gas is low) current flows to the heater to heat the sensor for accurate oxygen concentration detection.
HINT:
- Bank 1 refers to the bank that includes the cylinder No.1
- Sensor 2 refers to the sensor farther away from the engine body.
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 (test) mode.
c. Start the engine and let the engine idle for 60 seconds or more.
d. Drive the vehicle at 40 km/h (24 mph) or more for 40 seconds or more.
e. Let the engine idle for 10 seconds or more.
f. Perform steps (d) to (e) 9 times.
HINT: 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 from (c) to (f), then perform steps (c) to (f) again.
Step 1 - 3:
INSPECTION PROCEDURE
HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, this 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.