Troubleshooting
DTC P2A03 A/F SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 1)CIRCUIT DESCRIPTION
DTC Detecting Condition:
To obtain a high purification rate of the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used. 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 air fuel ratio sensor has the characteristic that it provides output voltage* being approximately proportional to the existing air-fuel ratio. The air fuel ratio sensor output voltage* is used to provide feedback for the ECM to control the air-fuel ratio.
By the air fuel ratio sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio and control the proper injection time immediately. If the air fuel ratio sensor is does not function, ECM is unable to perform the accurate air-fuel ratio control.
The air fuel ratio 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 temperature of the exhaust gas is low), the current flows to the heater to heat the sensor for the accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.
HINT:
- DTC P2A00 means malfunction related to bank 1 air fuel ratio sensor.
- DTC P2A03 means malfunction related to bank 2 air fuel ratio sensor.
- 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:
Step 1 - 2:
Step 2 (continued):
Step 3 - 4:
Step 5:
Step 6 - 10:
Step 11 - 16:
Step 17 - 18:
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
The narrowing down the trouble area is possible by performing ACTIVE TEST of the following "A/F CONTROL" (oxygen sensor or another can be distinguished).
a. Perform ACTIVE TEST by hand-held tester (A/F CONTROL).
HINT: "A/F CONTROL" is an ACTIVE TEST which changes the injection volume to -12.5% or +25%.
1. Connect the hand-held tester to the DLC3 on the vehicle.
2. Turn the ignition switch ON.
3. Warm up the engine with the engine speed at 2,500 rpm for approx. 90 sec.
4. Select the item "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL".
5. Perform "A/F CONTROL" when idle condition (press the right or left button).
Result:
Air fuel ratio sensor and oxygen sensor reacts in synchronizing with increase and decrease of injection volume (+25% -> rich output: 1 V, -12.5% -> lean output: 0 V)
NOTE: However, there is a few second delay in the sensor 1 (front air fuel ratio sensor) output. And there is about 20 seconds delay in the sensor 2 (rear oxygen sensor).
The following procedure of A/F CONTROL enable that to check its output (show its graph indication) of air fuel ratio sensor and oxygen sensor.
To display the graph indication. Select and push the "YES or NO" button 2 data "AFS B1 S1 and O2S B1 S2" or "AFS B2S1 and O2S B2S2" and press button "4" after selecting "ACTIVE TEST/ A/F CONTROL/USER DATA".
HINT:
- DTC P2A00 or P2A03 may be also detected, when the air fuel ratio is stuck rich or lean.
- 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, it 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.
CHECK FOR INTERMITTENT PROBLEMS
Hand-held tester only:
By putting the vehicle's ECM in the check mode, the 1 trip detection logic is possible instead of 2 trip detection logic and sensitivity the 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.
CONFIRMATION DRIVING PATTERN
1. Connect the hand-held tester to the DLC3. (*1)
2. Switch the hand-held tester from the normal mode to the check mode.(*1)
3. Start the engine and warm it up with all the accessory switches OFF.(*2)
4. Drive the vehicle at 60 - 120 km/h (38 - 75 mph) and engine speed at 1,400 - 3,200 rpm for 3 - 5 min.(*3)
HINT: If a malfunction exists, the MIL will light up during step. (*3)
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 (*2) and (*3), then perform steps (*2) and (*3) again.