SFI SYSTEM, Diagnostic DTC:P2A00, P2A03

DTC Code	DTC Name
P2A00	A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)
P2A03	A/F Sensor Circuit Slow Response (Bank 2 Sensor 1)

DESCRIPTION

Refer to DTC P2195 Click here.

Tech Tips

DTC P2A00 indicates malfunctions related to the bank 1 air fuel ratio sensor.
DTC P2A03 indicates malfunctions related to the bank 2 air fuel ratio 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 and located near the engine assembly.

DTC No.	DTC Detection Condition	Trouble Area
P2A00 P2A03	Calculated value for air fuel ratio sensor response rate deterioration level is less than threshold	Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor Air fuel ratio sensor heater ECM

DTC No.

DTC Detection Condition

Trouble Area

P2A00

P2A03

Calculated value for air fuel ratio sensor response rate deterioration level is less than threshold

Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit
Air fuel ratio sensor
Air fuel ratio sensor heater
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 air fuel ratio control is performed for approximately 10 seconds after preconditions are met in order to measure the air fuel ratio sensor response rate. During active air fuel ratio 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 air fuel ratio sensor response rate. The ECM receives a signal from the air fuel ratio sensor while performing active air fuel ratio control and uses it to calculate the air fuel ratio sensor response rate deterioration level.

If the value for air fuel ratio sensor response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and sets the DTC.

CONFIRMATION DRIVING PATTERN

Tech Tips

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

(a) Connect the intelligent tester to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester ON.
(d) Clear the DTCs Click here.
(e) Enter the following menus: Powertrain / Engine / Data List / Monitor Status.
(f) Check that O2S (A/FS) Monitor is Incmpl.
(g) Start the engine and warm it up.
(h) Drive the vehicle at between 80 km/h and 120 km/h (50 mph and 75 mph) for 3 minutes. However, the vehicle should be driven at a constant speed.
(i) Check O2S (A/FS) Monitor is Incmpl.
(j) Enter the following menus: Powertrain / Engine / DTC / Pending.
(k) Check if any DTCs (any pending DTCs) are set.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Intelligent tester 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 sensor, heated oxygen 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 intelligent tester.

Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
On the tester, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor.
Perform the Active Test 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 air fuel ratio and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

Tech Tips

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.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	+25%	Rich	Less than 3.0 V
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	-12.5%	Lean	More than 3.35 V
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	+25%	Rich	More than 0.55 V
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	-12.5%	Lean	Less than 0.4 V

Note

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.

Case	Air Fuel Ratio Sensor (Sensor 1) Output Voltage	Heated Oxygen Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1			-
2			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely rich or lean)

Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain / Engine / 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.

Tech Tips

DTC P2A00 or P2A03 may be also set, when the air fuel ratio is stuck rich or lean.
A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high air fuel ratio 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 intelligent tester. Freeze frame data records the engine condition 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.

PROCEDURE

CHECK ANY OTHER DTC OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester ON.
Enter the following menus: Powertrain / Engine / DTC.

Read the DTCs.

Result

Result	Proceed to
DTC P2A00 and/or P2A03 are output	A
DTC P2A00 and/or P2A03 and other DTCs are output	B

Tech Tips

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

GO TO DTC CHART Click here

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the air fuel ratio sensor connector.

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

Standard Resistance (Bank 1 Sensor 1)

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

Standard Resistance (Bank 2 Sensor 1)

Tester Connection	Condition	Specified Condition
1 (HA2A) - 2 (+B)	20°C (68°F)	1.8 to 3.4 Ω
1 (HA2A) - 4 (A2A-)	Always	10 kΩ or higher

Reconnect the air fuel ratio sensor connector.

REPLACE AIR FUEL RATIO SENSOR Click here

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

Disconnect the air fuel ratio sensor connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
E42-1 (HA1A) - E6-5 (HA1A)	Always	Below 1 Ω
E42-3 (A1A+) - E5-23 (A1A+)	Always	Below 1 Ω
E42-4 (A1A-) - E5-22 (A1A-)	Always	Below 1 Ω
E38-1 (HA2A) - E6-6 (HA2A)	Always	Below 1 Ω
E38-3 (A2A+) - E5-21 (A2A+)	Always	Below 1 Ω
E38-4 (A2A-) - E5-20 (A2A-)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
E42-1 (HA1A) or E6-5 (HA1A) - Body ground	Always	10 kΩ or higher
E42-3 (A1A+) or E5-23 (A1A+) - Body ground	Always	10 kΩ or higher
E42-4 (A1A-) or E5-22 (A1A-) - Body ground	Always	10 kΩ or higher
E38-1 (HA2A) or E6-6 (HA2A) - Body ground	Always	10 kΩ or higher
E38-3 (A2A+) or E5-21 (A2A+) - Body ground	Always	10 kΩ or higher
E38-4 (A2A-) or E5-20 (A2A-) - Body ground	Always	10 kΩ or higher

Reconnect the air fuel ratio sensor connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

PERFORM CONFIRMATION DRIVING PATTERN

NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / DTC / Pending.

Read the DTCs.

Result

Result	Proceed to
DTCs P2A00 and/or P2A03 are output	A
DTC is not output	B

CHECK FOR INTERMITTENT PROBLEMS Click here

REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT
PERFORM CONFIRMATION DRIVING PATTERN

NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / DTC / Pending.

Read the DTCs.

Result

Result	Proceed to
DTC is not output	A
DTCs P2A00 and/or P2A03 are output	B

CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (REFER TO DTC P0171 PROCEDURE) Click here

END