1Nz-Fe Engine Control. Dtc P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

DTC No.	DTC Detection Condition	Trouble Area
P2A00	Calculated value of Air-Fuel Ratio (A/F) sensor response rate deterioration level less than threshold (2 trip detection logic)	A/F sensor Intake system Fuel injector assembly Fuel pump Fuel line 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 control is performed for approximately 10 seconds after the 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 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 A/F sensor response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and stores the DTC.

Yaris. Ncp93, 131.1Nz-Fe Engine Control.Sfi System (For Sedan).
Dtc
P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

MONITOR STRATEGY

Related DTCs	P2A00: Air-Fuel Ratio (A/F) sensor slow response
Required Sensors/Components (Main)	A/F sensor
Required Sensors/Components (Related)	Vehicle speed sensor, Crankshaft position sensor
Frequency of Operation	Once per driving cycle
Duration	10 to 15 seconds
MIL Operation	2 driving cycles
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present	P0016 (VVT system- misalignment) P0031, P0032 (A/F sensor heater) P0100, P0102, P0103 (MAF meter) P0110, P0112, P0113 (IAT sensor) P0115, P0117, P0118 (ECT sensor) P0120 - P0123, P0220, P0222, P0223, P2135 (TP sensor) P0125 (Insufficient ECT for Closed Loop) P0128 (Thermostat) P0171, P0172 (Fuel system) P0301 - P0304 (Misfire) P0335 (CKP sensor) P0340 (CMP sensor) P0450 - P0453 (EVAP system) P0500 (VSS) P0505 (ISC) P0722 (VSS)
Active A/F control	Performing
Active A/F control performed when following conditions met	-
Engine coolant temperature	75°C (167°F) or more
Battery voltage	11 V or more
Idle	OFF
Engine RPM	Less than 4000 rpm
A/F sensor status	Activated
Fuel cut	OFF
Engine load	10 to 70%
Shift position	2 or higher
Catalyst monitor	Not yet
Mass air flow	4 to 17 gm/sec

TYPICAL MALFUNCTION THRESHOLDS

Response rate deterioration level

Less than 0.12 V

MONITOR RESULT

Refer to Checking Monitor Status (YARIS_NCP93 RM000000PDR0A3X.html).

CONFIRMATION DRIVING PATTERN

HINT:

Performing this confirmation pattern will activate the air fuel ratio sensor response monitor.

Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) (YARIS_NCP93 RM000000PDK0QGX.html).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor.
Check that O2 Sensor / Current is Incomplete.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
Drive the vehicle at approximately 60 km/h (38 mph) for 10 minutes or more in a city area.[B]
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Check the monitor result values on the Techstream by entering the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor / O2 Sensor / Details / RES RATE B1S1.
If the values indicated on the Techstream do not change, perform Readiness Monitor Drive Pattern for the air fuel ratio sensor and heated oxygen sensor (YARIS_NCP93 RM000000SXQ067X.html).
Note the value of Monitor Result.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
Read pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P2A00.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform the following procedure.

Drive the vehicle at a speed between 75 and 100 km/h (47 and 63 mph) for 10 minutes [D].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
Read pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2A00.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.

If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (YARIS_NCP93 RM000000PDK0QGX.html).
HINT:
1. If a permanent DTC is output, the system is malfunctioning.
2. If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

Refer to DTC P2195 (YARIS_NCP93 RM000000WC40K6X_07.html).

INSPECTION PROCEDURE

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:

DTC P2A00 may be stored, 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 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.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.

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

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

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

Read DTCs.
Result
Result
Proceed to
DTC P2A00 is output
A
DTC P2A00 and other DTCs are output
B
HINT:
If any DTCs other than P2A00 are output, troubleshoot those DTCs first.

Result
Result	Proceed to
DTC P2A00 is output	A
DTC P2A00 and other DTCs are output	B

GO TO DTC CHART (YARIS_NCP93 RM000000PDF0E6X.html)

A

2.PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)

Connect the Techstream to the DLC3.

Start the engine.

Turn the Techstream on.

Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.

Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.

Perform the Control the Injection Volume operation with the engine idling.

Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

HINT:

Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations.
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

Techstream Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
AFS Voltage B1S1 (Air fuel ratio)	-12%	Lean	Higher than 3.4 V
O2S B1S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
O2S B1S2 (Heated oxygen)	-12%	Lean	Below 0.4 V

Result
Status of AFS Voltage B1S1	Status of O2S B1S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Proceed to
Lean/Rich	Lean/Rich	Normal	A
Lean	Lean	Actual air fuel ratio lean	B
Rich	Rich	Actual air fuel ratio rich	B
Lean	Lean/Rich	Air fuel ratio sensor malfunction	C
Rich	Lean/Rich	Air fuel ratio sensor malfunction	C

Lean: During the Control the Injection Volume Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently below 0.4 V.
Rich: During the Control the Injection Volume Active Test, the AFS Voltage is consistently below 3.1 V, and the O2S is consistently higher than 0.55 V.
Lean/Rich: During the Control the Injection Volume Active Test, the output voltage of the heated oxygen sensor alternates correctly.

Refer to "Data List / Active Test" [AFS Voltage B1S1 and O2S B1S2] (YARIS_NCP93 RM000000PDN0J9X.html).

Go to step 4

Go to step 8

A

3.CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Clear DTCs (YARIS_NCP93 RM000000PDK0QGX.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON.

Turn the Techstream on.

Start the engine and warm it up.

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2A00.

Check the DTC judgment result.
Result
Result
Proceed to
NORMAL (DTC is not output)
A
ABNORMAL (DTC P2A00 is output)
B

Result
Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P2A00 is output)	B

Go to step 8

CHECK FOR INTERMITTENT PROBLEMS (YARIS_NCP93 RM000000PDQ0NOX.html)

4.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the C23 A/F sensor connector.

Measure the resistance of the A/F sensor connector.
Standard resistance:
Tester Connections
Specified Conditions
HA1A (1) - +B (2)
1.8 Ω to 3.4 Ω at 20°C (68°F)
HA1A (1) - A1A- (4)
10 kΩ or higher

Reconnect the A/F sensor connector.

REPLACE AIR FUEL RATIO SENSOR

OK

5.CHECK INTAKE SYSTEM

Check the intake system.

REPAIR OR REPLACE INTAKE SYSTEM

OK

6.CHECK FUEL PRESSURE

Check the fuel pressure (YARIS_NCP93 RM000001EF100YX_01_0002.html).

Go to step 12

OK

7.CHECK FUEL INJECTOR ASSEMBLY

Inspect the fuel injector assembly (YARIS_NCP93 RM000001EDQ046X.html).

REPLACE FUEL INJECTOR ASSEMBLY (YARIS_NCP93 RM000001EDS04FX.html)

OK

8.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor (YARIS_NCP93 RM000001CKA00YX.html).

NEXT

9.CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Clear DTCs (YARIS_NCP93 RM000000PDK0QGX.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON.

Turn the Techstream on.

Start the engine and warm it up.

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2A00.

Check the DTC judgment result.
Result
Result
Proceed to
ABNORMAL (DTC P2A00 is output)
A
NORMAL (DTC is not output)
B

END

A

10.REPLACE ECM

Replace the ECM (YARIS_NCP93 RM000001CN002AX.html).

NEXT

11.CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Clear DTCs (YARIS_NCP93 RM000000PDK0QGX.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON.

Turn the Techstream on.

Start the engine and warm it up.

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2A00.

Check that the DTC judgment result is NORMAL.

END

12.INSPECT FUEL PUMP

Inspect the fuel pump (YARIS_NCP93 RM000000SL602SX.html).

REPLACE FUEL PUMP (YARIS_NCP93 RM000001JUN00MX.html)

REPAIR OR REPLACE FUEL LINE

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