P2A00

2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2A00: A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)
P2A00 - A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

DESCRIPTION

HINT
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 P2195.





MONITOR DESCRIPTION





The output voltage of the A/F sensor varies in proportion to the air-fuel ratio. Based on these voltage variations, the ECM determines whether the actual air-fuel ratio is rich or lean, and makes adjustments to bring it close to the stoichiometric level. In addition, the ECM checks the fuel injection volume compensation value to determine whether the A/F sensor response time is normal or slow. The ECM calculates the ratio of the variations in both the A/F sensor output voltage and the fuel trim value.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

Refer to DTC P2195 P2195.

INSPECTION PROCEDURE

HINT
Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function 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 the Techstream.

- Connect the Techstream to the DLC3.

- Start the engine and turn the Techstream on.

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

- Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

- Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

- Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

HINT
- 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 in the fuel injection volume.

Standard:

Standard::

NOTICE:
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.





- Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.

- To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1 S1 and O2S B1 S2 then press the graph button on the Data List view.

HINT
- DTC P2A00 may be also set when the air-fuel ratio is stuck at 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 the Techstream. 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.
PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to the ON position.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs.

Result:





HINT
If any DTCs other than P2A00 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART Engine Control System - SFI System
A -- Continue to next step.

2. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Turn the Techstream on.

(d) Warm up the Air-Fuel Ratio (A/F) sensor at an engine speed of 2,500 rpm for 90 seconds.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / AFS Voltage B1 S1 and Engine Speed: then press the Record button.

(f) Check the A/F sensor voltage 3 times, when the engine is in each of the following conditions:

(1) While idling (check for at least 30 seconds)

(2) At an engine speed of approximately 2,500 rpm (without any sudden changes in engine speed)

(3) The engine speed is raised to 4,000 rpm and then the accelerator pedal is quickly released so that the throttle valve is fully closed.

Standard voltage:





(j) For more information, see the diagrams below.





HINT
- If the output voltage of the A/F sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have an open circuit. (This will also happen if the A/F sensor heater has an open circuit.)
- If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have a short circuit.
- The ECM stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the A/F sensor output voltage.
- When the vehicle is driven:
- The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this is translated to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
- The A/F sensor is a current output element; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage result.
NG -- INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
OK -- Continue to next step.

3. PERFORM CONFIRMATION DRIVING PATTERN

NEXT -- Continue to next step.

4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

(a) Read the DTCs using the Techstream.

(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

(c) Read the DTCs.

Result:





B -- CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
A -- Continue to next step.

5. REPLACE AIR FUEL RATIO SENSOR

(a) Replace the air fuel ratio sensor Removal.

NEXT -- Continue to next step.

6. PERFORM CONFIRMATION DRIVING PATTERN

NEXT -- Continue to next step.

7. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

(a) Read the DTCs using the Techstream.

(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

(c) Read the DTCs.

Result:





B -- REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN
A -- Continue to next step.

8. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST

(a) Has the vehicle run out of fuel in the past?

NO -- CHECK FOR INTERMITTENT PROBLEMS

YES -- DTC CAUSED BY RUNNING OUT OF FUEL

9. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

(a) Disconnect the A3 A/F sensor connector.





(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:





(c) Reconnect the A/F sensor connector.

NG -- REPLACE AIR FUEL RATIO SENSOR Removal
OK -- Continue to next step.

10. INSPECT EFI RELAY

(a) Remove the EFI relay from the engine room relay block.





(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:





(c) Reinstall the EFI relay.

NG -- REPLACE EFI RELAY
OK -- Continue to next step.

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

(a) Disconnect the A3 A/F sensor connector.





(b) Turn the ignition switch to the ON position.

(c) Measure the voltage according to the value(s) in the table below.

Standard voltage:





(d) Turn the ignition switch off.

(e) Disconnect the E8 ECM connector.

(f) Measure the resistance according to the value(s) in the table below.

Standard resistance:









(g) Reconnect the A/F sensor connector.

(h) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

12. CHECK AIR INDUCTION SYSTEM

(a) Check the air induction system for vacuum leakage.

OK:

No leakage from air induction system.

NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.

13. CHECK PCV HOSE CONNECTIONS

OK:

PCV hose is connected correctly and is not damaged.

NG -- REPAIR OR REPLACE PCV HOSE
OK -- Continue to next step.

14. CHECK FUEL PRESSURE

(a) Check the fuel pressure Component Tests and General Diagnostics.

NG -- REPAIR OR REPLACE FUEL SYSTEM
OK -- Continue to next step.

15. INSPECT FUEL INJECTOR

(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).

NG -- REPLACE FUEL INJECTOR Removal
OK -- Continue to next step.

16. REPLACE AIR FUEL RATIO SENSOR

(a) Replace the air fuel ratio sensor Removal.

NEXT -- Continue to next step.

17. PERFORM CONFIRMATION DRIVING PATTERN

NEXT -- Continue to next step.

18. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

(a) Read the DTCs using the Techstream.

(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

(c) Read the DTCs.

Result:





B -- REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN
A -- Continue to next step.

19. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST

(a) Has the vehicle run out of fuel in the past?

NO -- CHECK FOR INTERMITTENT PROBLEMS

YES -- DTC CAUSED BY RUNNING OUT OF FUEL