Troubleshooting
DTC P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)CIRCUIT DESCRIPTION
DTC Detecting 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 A/F sensor has the characteristic that provides output voltage* approximately proportional to the existing air-fuel ratio. The A/F sensor output voltage* is used to provide feedback for the ECM to control the air-fuel ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to perform accurate air-fuel ratio control.
The A/F sensor is equipped with 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.
*: The voltage value changes at the inside of the ECM only.
HINT:
- If DTC P2A00 is displayed, check Bank 1 Sensor 1 circuit.
- If DTC P2A03 is displayed, check Bank 2 Sensor 1 circuit.
- Bank 1 refers to the bank that includes cylinder No.1.
- Bank 2 refers to the bank that includes cylinder No.2.
- Sensor 1 refers to the sensor closest to the engine body.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
1. Connect the hand-held tester to the DLC3.
2. Switch the hand-held tester from normal mode to check mode.
3. Start the engine and warm it up for 2 min. or more with all accessory switches OFF.
4. Drive the vehicle at 60 - 120 km/h (38 - 75 mph) and engine speed at 1,600 - 3,200 rpm for 3 - 5 minutes
HINT: If a malfunction exists, the MIL will light up during step (4).
NOTE:
If the conditions in this test are not strictly followed, detection of the malfunction will impossible.
If you do not have a hand-held tester, turn the ignition switch OFF after performing steps (3) and (4), then perform steps (3) and (4) again.
Step 1:
Step 2:
Step 2 (Contd.) - Step 3:
Step 4 - 8:
Step 9 - 13:
Step 14 - 17:
INSPECTION PROCEDURE
HINT: Read freeze frame data using hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel was ratio lean or rich, etc. at the time of the malfunction.
CHECK FOR INTERMITTENT PROBLEMS
HAND-HELD TESTER only:
By putting the vehicle's ECM in check mode, the 1 trip detection logic is possible instead of the 2 trip detection logic and the 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.