P2A00

3MZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2A00: A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

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

DTC P2A03 - A/F Sensor Circuit Slow Response (Bank 2 Sensor 1)

DESCRIPTION

- DTC P2A00 indicates malfunctions related to the bank 1 A/F sensor.
- DTC P2A03 indicates malfunctions related to the bank 2 A/F sensor.
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that includes cylinder No. 2.
- Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

The A/F sensor generates voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM (Included in HV control ECU) with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.
A three-way catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxides (NOx) into less harmful substances. To allow the TWC to function effectively, it is necessary to keep the air-fuel ratio of the engine near the stoichiometric air-fuel ratio.
*: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.









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 (Included in HV control ECU) 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 A/F sensor output voltage and the fuel trim value.





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





MONITOR RESULT

The monitor result (mode 6) allows the OBD scan tool to display the monitor status, test value and test limit.
A problem in this component can be found by comparing the test value and test limit. This procedure is described in "CHECKING MONITOR STATUS".

- TID (Test Identification) is assigned to each emission-related component.
- TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
- CID (Component Identification) is assigned to each test value.
- Unit Conversion is used to calculate the test value indicated on generic OBD scan tools.

TID $06: A/F Sensor





WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Techstream only:
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 Techstream.
1 Connect Techstream to the DLC3.
2 Put the engine in inspection mode Inspection Mode Procedure.
3 Start the engine and turn the tester ON.
4 Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
5 On Techstream, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
6 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).
7 Monitor the output voltages of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
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:





NOTE: 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 B1 S1 or AFS B2 S1 and O2S B1 S2 or O2S B2 S2 then press the graph button on the Data List view.
HINT:
- DTC P2A00 or P2A03 may also be 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 Techstream. The ECM (Included in HV control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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 ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
(e) Read the DTCs.
Result:





HINT: If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR)
(a) Connect Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Start the engine.
(d) Turn the tester ON.
(e) Warm up the Air-Fuel Ratio (A/F) sensor at an engine speed of 2,500 rpm for 90 seconds.
(f) On the tester, enter the following menus: Powertrain / Engine and ECT / Data List / AFS B1 S1 or AFS B2 S7 and Engine Speed.
(g) Check the the A/F sensor voltage three 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) Raise the engine speed to 4,000 rpm and then quickly release the accelerator pedal so that the throttle valve is fully closed.
Standard voltage:





HINT: 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 (Included in HV control ECU) 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.
- The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
- When the vehicle is driven: The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. The vehicle translates this as 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
OK -- Continue to next step.
3. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
Result:






B -- CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
A -- Continue to next step.
5. REPLACE AIR FUEL RATIO SENSOR
NEXT -- Continue to next step.
6. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
7. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
Result:






B -- REPLACE HV CONTROL ECU AND PERFORM CONFIRMATION DRIVING PATTERN
A -- Continue to next step.
8. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO -- CHECK FOR INTERMITTENT PROBLEMS
YES -- DTC CAUSED BY RUNNING OUT OF FUEL
9. INSPECT AIR FUEL RATIO SENSOR





(a) Disconnect the A3 or A4 A/F sensor connector.
(b) Measure the resistance between the terminals of the A/F sensor connector.
Standard resistance:





(c) Reconnect the A/F sensor connector.
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- Continue to next step.
10. INSPECT A/F RELAY





(a) Remove the A/F relay from the engine room R/B.
(b) Measure A/F relay resistance.
Standard resistance:





(c) Reinstall the A/F relay.
NG -- REPLACE A/F RELAY
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (A/F SENSOR -HV CONTROL ECU)





(a) Disconnect the A3 and A4 A/F sensor connectors.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage between the +B terminal of the A/F sensor connector and body ground.
Standard voltage:





(d) Turn the ignition switch off.
(e) Disconnect the H33 HV control ECU connector.
(f) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






Standard resistance (Check for short):





(g) Reconnect the HV control ECU connector.
(h) Reconnect the A/F sensor 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
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 Testing and Inspection.
Standard:
304 to 343 kPa (3.1 to 3.5 kgf/cm2, 44.1 to 49.7 psi)
NG -- REPAIR OR REPLACE FUEL SYSTEM
OK -- Continue to next step.
15. INSPECT FUEL INJECTOR
(a) Check the injector injection Testing and Inspection.
Standard:
13 cm3 (0.8 cu in.) or less
NG -- REPLACE FUEL INJECTOR ASSEMBLY
OK -- Continue to next step.
16. REPLACE AIR FUEL RATIO SENSOR
NEXT -- Continue to next step.
17. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
18. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
Result:






B -- REPLACE HV CONTROL ECU
A -- Continue to next step.
19. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO -- CHECK FOR INTERMITTENT PROBLEMS
YES -- DTC CAUSED BY RUNNING OUT OF FUEL