P2A00

2GR-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)

CAUTION / NOTICE / HINT
HINT:
- 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.

DESCRIPTION

The A/F sensor generates a 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. 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), hydro carbon (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.

HINT:
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that includes cylinder No. 2.
- When any of these DTCs are set, check the A/F sensor voltage output by selecting the following menu items on Techstream: Powertrain / Engine and ECT / Data List / A/F Control System / AFS B1 S1 or AFS B2 S1.
- Short-term fuel trim values can also be read using Techstream.
- The ECM regulates the voltages at the A1A+, A2A+, A1A- and A2A- terminals of the ECM to a constant level. Therefore, the A/F sensor voltage output cannot be confirmed without using Techstream.
- If an A/F sensor malfunction is detected, the ECM sets a DTC.

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 ratio control is performed for approximately 10 seconds after preconditions are met in order to measure the A/F sensor response rate. During active A/F ratio control, the ECM forcibly increases and decreases the injection volume to 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 ratio control and uses it to calculate the A/F sensor response rate deterioration level.
If the 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.

CONFIRMATION DRIVING PATTERN
HINT: Performing this confirmation driving pattern will activate the A/F sensor response monitor.

1. Connect Techstream to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn the tester on.
4. Clear the DTCs (where set).
5. Select the following menu items: Powertrain / Engine and ECT / Monitor / Result.
6. Check that RES RATE B1S1 and RES RATE B2S1 is Incomplete.
7. Start the engine and warm it up (Procedure "A").
8. Drive the vehicle at between 25 mph and 75 mph (40 km/h and 120 km/h) for 3 minutes. However, the vehicle should be driven at a constant speed (Procedure "B").
9. Check the monitor result values on Techstream by selecting the following menu items: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details / RES RATE B1S1 and RES RATE B2S1.
10. If the values indicated on the tester do not change, perform READINESS MONITOR DRIVE PATTERN for the A/F sensor and the heated oxygen sensor Monitors, Trips, Drive Cycles and Readiness Codes.
HINT: Completion of all A/F sensor monitors is required to change the value in test result.

11. Note the value of the Monitor Result.
12. Select the following menu items: Powertrain / Engine and ECT / Trouble Code / Pending.
13. Check if any DTCs (any pending DTCs) are set.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

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 Techstream.
1. Connect 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. Select the following menu items on the tester: 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 voltage outputs 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 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.

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) Select the following menu items: 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. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

(a) Disconnect the A5 or A6 A/F sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
Bank 1

Bank 2

C -- REPLACE AIR FUEL RATIO SENSOR
B -- REPLACE AIR FUEL RATIO SENSOR
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

(a) Disconnect the A5 or A6 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 E10 ECM connector.
(f) Measure the resistance according to the value(s) in the table below.
Standard resistance:
Check for open

Check for short

(g) Reconnect the ECM connector.
(h) Reconnect the A/F sensor connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F SENSOR - ECM)
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 Techstream.
(b) Select the following menu items: Powertrain / Engine and ECT / Trouble Code / Pending.
Result:

B -- CHECK FOR INTERMITTENT PROBLEMS
A -- Continue to next step.
6. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor (for 2WD model Removal or 4WD model Removal).
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 Techstream.
(b) Select the following menu items: Powertrain / Engine and ECT / Trouble Code / Pending.
Result:

B -- REPLACE ECM
A -- END