Troubleshooting
DTC P0130 HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 1)CIRCUIT DESCRIPTION
DTC Detection Condition:
To obtain 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 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 feedback to the computer for control of 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 is 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 oxygen sensor causes an output of abnormal electromotive force, the ECM becomes unable to perform accurate air-fuel ratio control.
The main 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 to heat the sensor for the accurate oxygen concentration detection.
After confirming DTC P0125, use the OBD II scan tool or LEXUS hand-held tester to confirm the output voltage of the heated oxygen sensor (bank 1, 2 sensor 1) from the CURRENT DATA. If the voltage output of the heated oxygen sensor is less than 0.1 V the heated oxygen sensor circuit may be open or short.
HINT:
- Bank 1 refers to bank that includes cylinder No.1.
- Bank 2 refers to bank that does not include cylinder No.1
- Sensor 1 refers to the sensor closer to the engine body.
- The heated oxygen sensors output voltage and the short-term fuel trim value can be read using the OBD II scan tool or LEXUS hand-held tester.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
a. Connect the LEXUS hand-held tester to the DLC3.
b. Switch the LEXUS hand-held tester from Normal Mode to Check Mode.
c. Start the engine and let the engine idle for 100 seconds or more.
d. Drive the vehicle at 40 km/h (24 mph) or more for 20 seconds or more.
e. Let the engine idle for 20 seconds or more.
f. Let the engine idle for 30 seconds.
HINT: If a malfunction exists, the MIL will light up during step (f).
NOTE: If the conditions in this test are not strictly followed, detection of the malfunction will impossible.
If you do not have a LEXUS hand-held tester, turn the ignition switch OFF after performing steps (c) to (f), then perform steps (c) to (f) again.
Step 1 - 2:
Step 3 - 4:
Step 5 - 6:
Step 8:
INSPECTION PROCEDURE
NOTE: If the vehicle is short of fuel, the air-fuel ratio becomes LEAN and DTC P0125 will be recorded, and the check engine warning light then comes on.
CHECK FOR INTERMITTENT PROBLEMS
LEXUS hand-held tester only:
By putting the vehicle's ECM in the check mode, the 1 trip detection logic is possible instead of the 2 trip detection logic and sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
1. Clear the DTC.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.