SFI SYSTEM (w/ Secondary Air Injection System), Diagnostic DTC:P2A00

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

DESCRIPTION

Tech Tips

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

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 the 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 ratio 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 ratio 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 measures the A/F sensor response rate.

The ECM receives a signal from the A/F sensor while performing active A/F ratio 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 threshold, the ECM interprets this as a malfunction and sets the DTC.

A01BGOVE01

CONFIRMATION DRIVING PATTERN

Tech Tips

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

A01BCJUE32

  1. Connect an intelligent tester to the DLC3.

  2. Turn the ignition switch to the ON position.

  3. Turn the tester ON.

  4. Clear DTCs (where set).

  5. Start the engine and warm it up (1).

  6. Drive the vehicle at between 40 km/h and 120 km/h (25 mph and 75 mph) for 3 minutes. However, the vehicle should be driven at a constant speed (2).

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

  8. Check if any DTCs (any pending DTCs) are set.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor operation provided in the Active Test. The Control the Injection Volume for A/F Sensor 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 for A/F Sensor operation using an intelligent tester.


  1. Connect an intelligent tester to the DLC3.

  2. Start the engine and turn the tester ON.

  3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.

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

  5. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition.

  6. Monitor the voltage outputs of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the tester.

Tech Tips


  • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.

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

Voltage

Tester Display

(Sensor)

 Injection Volumes Status Voltages

AFS Voltage B1S1

(A/F)

 +25 % Rich Less than 3.1

AFS Voltage B1S1

(A/F)

 -12.5 % Lean More than 3.4

O2S B1S2

(HO2)

 +25 % Rich More than 0.5

O2S B1S2

(HO2)

 -12.5 % Lean Less than 0.4

CAUTION:

The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

Case

A/F Sensor (Sensor 1)

Output Voltage

HO2 Sensor (Sensor 2)

Output Voltage

 Mainly Suspected Trouble Areas
1

Injection volume

+25 %

-12.5 %

 A01BAGF

Injection volume

+25 %

-12.5 %

 A01BAGF -

Output voltage

More than 3.4 V

Less than 3.1 V

 A01BF8P

Output voltage

More than 0.5 V

Less than 0.4 V

 A01BBCR
2

Injection volume

+25 %

-12.5 %

 A01BAGF

Injection volume

+25 %

-12.5 %

 A01BAGF

  • A/F sensor

  • A/F sensor heater

  • A/F sensor circuit

Output voltage

Almost no reaction

 A01BD50

Output voltage

More than 0.5 V

Less than 0.4 V

 A01BBCR
3

Injection volume

+25 %

-12.5 %

 A01BAGF

Injection volume

+25 %

-12.5 %

 A01BAGF

  • HO2 sensor

  • HO2 sensor heater

  • HO2 sensor circuit

Output voltage

More than 3.4 V

Less than 3.1 V

 A01BF8P

Output voltage

Almost no reaction

 A01BD50
4

Injection volume

+25 %

-12.5 %

 A01BAGF

Injection volume

+25 %

-12.5 %

 A01BAGF

  • Injector

  • Fuel pressure

  • Gas leakage from exhaust system

(Air-fuel ratio extremely lean or rich)

Output voltage

Almost no reaction

 A01BD50

Output voltage

Almost no reaction

 A01BD50

Tech Tips


  • DTC P2A00 may be also set 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 rich.

  • 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 lean.

  • Read freeze frame data using an intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

  • DTC P2A00 may also be set when the sensor element is electrically clogged or contaminated.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00)


    1. Connect an intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the tester ON.

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

    5. Read DTCs.

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

      If any DTCs relating to the A/F sensor (DTCs for the A/F sensor heater or A/F sensor admittance) are output, troubleshoot those DTCs first.


    B

    GO TO DTC CHART

    A

  2. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. A01BEQSE27

      Disconnect the D33 Air-Fuel Ratio (A/F) sensor connector.

    2. Measure the resistance between the terminals of the A/F sensor connector.

      Resistance
      Tester Connections Specified Conditions
      HA1A (1) - +B (2) 1.8 to 3.4 Ω at 20°C (68°F)
      HA1A (1) - A1A- (4) 10 kΩ or higher

    3. Reconnect the air-fuel ratio sensor connector.


    NG

    REPLACE AIR FUEL RATIO SENSOR

    OK

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


    1. A01BH8RE01

      Disconnect the D33 A/F sensor connector.

    2. Turn the ignition switch to the ON position.

    3. Measure the voltage between the +B terminal of the A/F sensor connector and body ground.

      Voltage
      Tester Connections Specified Conditions
      +B (D33-2) - Body ground 9 to 14 V

    4. Turn the ignition switch to OFF.

    5. Disconnect the D1 ECM connector.

    6. Measure the resistance.

      Resistance (Check for open)
      Tester Connections Specified Conditions
      HA1A (D33-1) - HA1A (D1-1) Below 1 Ω
      A1A+(D33-3) - A1A+ (D1-21) Below 1 Ω
      A1A- (D33-4) - A1A- (D1-31) Below 1 Ω
      Resistance (Check for short)
      Tester Connections Specified Conditions
      HA1A (D33-1) or HA1A (D1-1) - Body ground 10 kΩ or higher
      A1A+ (D33-3) or A1A+ (D1-21) - Body ground 10 kΩ or higher
      A1A- (D33-4) or A1A- (D1-31) - Body ground 10 kΩ or higher

    7. Reconnect the ECM connector.

    8. Reconnect the A/F sensor connector.

      A01BI28E02

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. PERFORM CONFIRMATION DRIVING PATTERN


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position and turn the tester ON.

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

    4. Reading pending 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. CONFIRM CONFIRMATION DRIVING PATTERN


    NEXT

  8. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position and turn the tester ON.

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

    4. Reading pending DTCs.

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

    B

    CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

    A

    END