Except PZEV Engine

DTC P2A00 A/F SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)

CIRCUIT DESCRIPTION

DTC Detecting Condition:

HINT:
This DTC is recorded when A/F sensor is in a malfunction, although the caption is oxygen sensor. To obtain a high purification rate of 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 a characteristic of providing 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 the 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 temperature of the exhaust gas is low), 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.

Wiring Diagram:

Step 1:

Step 2:

Step 3 - 4:

Step 5:

Step 6 - 10:

Step 11 - 16:

Step 17 - 18:

INSPECTION PROCEDURE

HINT:
- DTC P2A00 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.

CONFIRMATION DRIVING PATTERN

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.

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 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 (See step 2).
2. Set the check mode (See step 3).
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.