SFI SYSTEM, Diagnostic DTC:P2A00

DTC Code DTC Name
P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

CAUTION / NOTICE / HINT

Tech Tips

Sensor 1 refers to the sensor mounted before the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

DESCRIPTION

Refer to DTC P2195 Click here.

DTC No. DTC Detection Conditions Trouble Areas
P2A00 Calculated value for air-fuel ratio (A/F) sensor response rate deterioration level is less than threshold

  • Open or short in A/F sensor circuit

  • A/F sensor

  • ECM

MONITOR DESCRIPTION

After engine is warmed up, the ECM performs air-fuel ratio feedback control to maintain the air-fuel ratio at the stoichiometric level. In addition, active A/F control is performed for approximately 10 seconds after preconditions are met in order to measure the A/F sensor response rate. During active A/F control, the ECM forcibly increases and decreases the injection volume a certain amount, based on the stoichiometric air-fuel ratio learned during normal air-fuel ratio control, and measure the A/F sensor response rate.

The ECM receives a signal from the A/F sensor while performing active A/F control and uses it to calculate the A/F sensor response rate deterioration level.

If the value for A/F sensor response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and sets the DTC.

A01DZE8E03

CONFIRMATION DRIVING PATTERN

Tech Tips

Performing this confirmation pattern will activate the A/F sensor response monitor.

A01DX32E17

(a) Connect the intelligent tester to the DLC3.

(b) Turn the ignition switch to ON and turn the intelligent tester ON.

(c) Start the engine and warm it up.

(d) Drive the vehicle between 40 and 120 km/h (25 and 75 mph) for 3 minutes. However, the vehicle should be driven at a constant speed.

Note

If the conditions in this test are not strictly followed, no malfunction will be detected.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Intelligent tester only:

Malfunctioning areas can be identified by performing the "Control the Injection Volume" function provided in the Active Test. The "Control the Injection Volume" function can help to determine whether the Air-fuel Ratio (A/F) sensor, heated oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the "Control the Injection Volume" operation using intelligent tester.


  1. Connect the intelligent tester to the DLC3.

  2. Start the engine and turn the intelligent tester ON.

  3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.

  4. On the intelligent tester, select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.

  5. Perform the "Control the Injection Volume" operation with the engine in an idling condition (press the right or left button to change the fuel injection volume).

  6. Monitor the output voltage of the A/F and Heated oxygen sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.

Tech Tips


  • The "Control the Injection Volume" operation lowers the fuel injection volume by 12.5% or increases the injection volume by 24.8%.

  • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Standard

Tester Display

(Sensor)

 Injection Volume Status Voltage

AFS B1 S1

(A/F)

 +24.8% Rich Less than 3.0 V

AFS B1 S1

(A/F)

 -12.5% Lean More than 3.35 V

O2S B1 S2

(HO2)

 +24.8% Rich More than 0.55 V

O2S B1 S2

(HO2)

 -12.5% Lean Less than 0.4 V

Note

The S/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.

Case

A/F Sensor (Sensor 1)

Output Voltage

HO2 Sensor (Sensor 2)

Output Voltage

 Main Suspected Trouble Areas
1

Injection Volume

+24.8%

-12.5%

 A01DUZ5

Injection Volume

+24.8%

-12.5%

 A01DUZ5 -

Output Voltage

More than 3.35 V

Less than 3.0 V

 A01DW5S

Output Voltage

More than 0.55 V

Less than 0.4 V

 A01DVNA
2

Injection Volume

+24.8%

-12.5%

 A01DUZ5

Injection Volume

+24.8%

-12.5%

 A01DUZ5

  • A/F sensor

  • A/F sensor heater

  • A/F sensor circuit

Output Voltage

Almost

no reaction

 A01E300

Output Voltage

More than 0.55 V

Less than 0.4 V

 A01DVNA
3

Injection Volume

+24.8%

-12.5%

 A01DUZ5

Injection Volume

+24.8%

-12.5%

 A01DUZ5

  • HO2 sensor

  • HO2 sensor heater

  • HO2 sensor circuit

Output Voltage

More than 3.35 V

Less than 3.0 V

 A01DW5S

Output Voltage

Almost

no reaction

 A01E300
4

Injection volume

+24.8%

-12.5%

 A01DUZ5

Injection Volume

+24.8%

-12.5%

 A01DUZ5

  • Injector

  • Fuel pressure

  • Gas leakage from exhaust system

    (Air-fuel ratio extremely lean or rich)

Output Voltage

Almost

no reaction

 A01E300

Output Voltage

Almost

no reaction

 A01E300

Tech Tips


  • DTC P2A00 may also be detected when the air-fuel ratio is stuck rich or lean.

  • A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run with a rich air-fuel mixture.

  • A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run with a lean air-fuel mixture.

  • Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK OTHER DTC OUTPUT (IN ADDITION TO A/F SENSOR DTC)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / DTC.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed to
      P2A00 A
      P2A00 and other DTCs B

      Tech Tips

      If any other DTCs besides P2A00 are output, perform troubleshooting for those DTCs first.


    B

    GO TO RELEVANT DTC CHART

    A

  2. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

    A01DVTYE06

    1. Disconnect the A18 sensor connector.

    2. Measure the resistance of the sensor.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 (HT1A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω
      1 (HT1A) - 4 (A1A-) Always 10 kΩ or higher

    NG

    REPLACE AIR FUEL RATIO SENSOR

    OK

  3. CHECK WIRE HARNESS (A/F SENSOR - ECM)

    A01DW7BE09

    1. Disconnect the A18 A/F sensor connector.

    2. Turn the ignition switch ON.

    3. Measure the voltage of the wire harness side connector.

      Standard voltage
      Tester Connection Specified Condition
      A18-2 (+B) - Body ground 9 to 14 V

    4. Turn the ignition switch OFF.

    5. Disconnect the E12 ECM connector.

    6. Measure the resistance of the wire harness side connectors.

      Standard resistance
      Tester Connection Specified Condition
      A18-1 (HT1A) - E12-1 (HA1A) Below 1 Ω
      A18-3 (A1A+) - E12-21 (A1A+) Below 1 Ω
      A18-4 (A1A-) - E12-31 (A1A-) Below 1 Ω
      A18-1 (HT1A) or E12-1 (HA1A) - Body ground 10 kΩ or higher
      A18-3 (A1A+) or E12-21 (A1A+) - Body ground 10 kΩ or higher
      A18-4 (A1A-) or E12-31 (A1A-) - Body ground 10 kΩ or higher
      A01DVTJE17

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  4. PERFORM CONFIRMATION DRIVING PATTERN


    NEXT

  5. CHECK IF DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT/ DTC.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed to
      P2A00 A
      No output B

    B

    CHECK FOR INTERMITTENT PROBLEMS

    A

  6. REPLACE AIR FUEL RATIO SENSOR


    NEXT

  7. PERFORM CONFIRMATION DRIVING PATTERN


    NEXT

  8. CHECK IF DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / DTC.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed to
      No output A
      P2A00 B

    B

    CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (REFER TO DTC P0171 PROCEDURE)

    A

    END