P2A00

2UZ-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

HINT:
- Although the DTC titles refer to the "oxygen sensor", these DTCs relate to the Air Fuel Ratio (A/F) sensor.
- 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 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. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and the sensor activation is accelerated.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
HINT: *: Value changes inside the ECM. Since the A/F sensor is the current output element, the 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.









- 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 No. 1 cylinder.
- Bank 2 refers to the bank that includes No. 2 cylinder.
- Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and is located near the engine assembly.

MONITOR DESCRIPTION

After engine is warmed up, the ECM performs air fuel ratio feedback control to regulate the air fuel ratio at stoichiometric ratio. In addition, this vehicle performs Active Air Fuel Ratio (A/F) Control for approximately 10 seconds after preconditions are met in order to measure the A/F sensor response rate. During active air fuel ratio control, the ECM forcibly increases and decreases the injection volume a certain amount based on learned stoichiometric air fuel ratio during usual air fuel feedback control, and measures 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 test 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.





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

CONFIRMATION DRIVING PATTERN
HINT:
- This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.
- Performing this confirmation driving pattern will activate the Heated Oxygen (HO2) sensor monitor. (The catalyst monitor is performed simultaneously.) This is very useful for verifying the completion of a repair.
NOTE: This test will not be completed if the vehicle is driven under absolutely constant speed conditions such as with cruise control activated.





1 Connect the Techstream to the DLC3.
2 Turn the ignition switch ON.
3 Turn the tester ON.
4 Clear DTCs DTC Check / Clear.
5 Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more [A].
6 Drive the vehicle at between 60 km/h and 120 km/h (40 mph and 75 mph) for at least 10 minutes or more [B].
7 Drive the vehicle 60 km/h (40 mph) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times [C].
8 Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
9 Input DTCs: P2A00 and P2A03.
10 Check that Monitor is NORMAL. If Monitor is INCOMPLETE, perform the drive pattern adding the vehicle speed and using the second gear to decelerate the vehicle.

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 the Techstream.
1 Connect the Techstream to the DLC3.
2 Start the engine and turn the tester ON.
3 Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
4 On the Techstream, enter the following menus: 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 (press the RIGHT or LEFT button to change the fuel injection volume).
6 Monitor the output voltages of the A/F and HO2 sensors (AFS B1S1 (AFS B2S1) and O2S B1S2 (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 and decreases in the fuel injection volume.

Standard Voltage:





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 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2.
HINT:
- 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 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 AND/OR P2A03)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(d) Read the DTCs.
Result:





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

B -- GO TO DTC CHART
A -- Continue to next step.
2. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)





(a) Disconnect the A41 or A42 Air Fuel Ratio (A/F) sensor connector.
(b) Measure the resistance 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.
3. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)





(a) Disconnect the A41 or A42 A/F sensor connector.
(b) Turn the ignition switch ON.
(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 E6 ECM connector.
(f) Measure the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):










(g) Reconnect the A/F sensor connector.
(h) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
5. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
Result:






B -- CHECK FOR INTERMITTENT PROBLEMS
A -- Continue to next step.
6. REPLACE AIR FUEL RATIO SENSOR
NEXT -- Continue to next step.
7. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
8. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
Result:






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