GSIC - Global Service Information Center

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

## for Preparation Click here

HINT:

  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

1. Open or short in A/F sensor circuit
2. A/F sensor
3. 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.

## CONFIRMATION DRIVING PATTERN

HINT:

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

(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.

NOTICE:

  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

HINT:

  Intelligent tester only:

  Malfunctioning areas can be found by performing the Active Test / A/F Control operation. The A/F Control operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.

  (a) Perform Active Test using the intelligent tester.

HINT:

  The A/F Control operation lowers the injection volume by 12.5% or increases the injection volume by 25%.

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 / A/F Control.
5. Select the following monitor items: AFS B1 S1 and O2S B1 S2.
6. Perform the A/F Control operation with the engine in an idling condition (press the right or left button).

HINT:

1. The A/F Control operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
2. 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) | +25% | Rich | Less than 3.0 V
  AFS B1 S1 (A/F) | -12.5% | Lean | More than 3.35 V
  O2S B1 S2 (HO2) | +25% | Rich | More than 0.55 V
  O2S B1 S2 (HO2) | -12.5% | Lean | Less than 0.4 V

NOTICE:

  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 +25% -12.5% |  | Injection Volume +25% -12.5% |  | -
Output Voltage More than 3.35 V Less than 3.0 V |  | Output Voltage More than 0.55 V Less than 0.4 V |

2

Injection Volume
+25%
-12.5%

Injection Volume
+25%
-12.5%

1. A/F sensor
2. A/F sensor heater
3. A/F sensor circuit

Output Voltage Almost no reaction |  | Output Voltage More than 0.55 V Less than 0.4 V |

3

Injection Volume
+25%
-12.5%

Injection Volume
+25%
-12.5%

1. HO2 sensor
2. HO2 sensor heater
3. HO2 sensor circuit

Output Voltage More than 3.35 V Less than 3.0 V |  | Output Voltage Almost no reaction |

4

Injection volume
+25%
-12.5%

Injection Volume
+25%
-12.5%

1. Injector
2. Fuel pressure
3. Gas leakage from exhaust system
   (Air-fuel ratio extremely lean or rich)

Output Voltage Almost no reaction |  | Output Voltage Almost no reaction |

1. The following A/F Control procedure enables the technician to check and graph the output voltages of both A/F sensor and heated oxygen sensor.
2. To display the graph, select the following menu items on the tester: View / Line graph.

HINT:

1. DTC P2A00 may also be detected when the air-fuel ratio is stuck rich or lean.
2. 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.
3. 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.
4. 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.

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

1. Connect the intelligent tester to the DLC3.

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

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

1. Read DTCs.

   Result:

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

   HINT:
     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)

1. Disconnect the A18 sensor connector.

1. Measure the resistance of the sensor.

   Standard resistance:

     Tester Connection | Condition | Specified Condition
     1 (HT) -2 (+B) | 20°C (68°F) | 1.8 to 3.4 Ω
     1 (HT) -4 (AF-) | Always | 10 kΩ or higher

| NG |

REPLACE AIR FUEL RATIO SENSOR

OK |

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

1. Disconnect the A18 A/F sensor connector.

1. Turn the ignition switch ON.

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

   Standard voltage:

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

1. Turn the ignition switch OFF.

1. Disconnect the E12 ECM connector.

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

   Standard resistance:

     Tester Connection | Specified Condition
     A18-1 (HT) - E12-1 (HA1A) | Below 1 Ω
     A18-3 (AF+) - E12-21 (A1A+) | Below 1 Ω
     A18-4 (AF-) - E12-31 (A1A-) | Below 1 Ω
     A18-1 (HT) or E12-1 (HA1A) - Body ground | 10 kΩ or higher
     A18-3 (AF+) or E12-21 (A1A+) - Body ground | 10 kΩ or higher
     A18-4 (AF-) or E12-31 (A1A-) - Body ground | 10 kΩ or higher

| 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.

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

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

1. 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.

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

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

1. 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