P2A00

2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2A00,P2A03: 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 (HOx) 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:
- DTCs P2195 and P2196 indicate malfunctions related to the bank 1 A/F sensor circuit.
- DTCs P2197 and P2198 indicate malfunctions related to the bank 2 A/F sensor circuit.
- 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 the 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 the 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 the 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 the Techstream to the DLC3 (Procedure "A").
2 Turn the ignition switch to ON (Procedure "B").
3 Turn the Techstream on (Procedure "C").
4 Clear the DTCs (where set) (Procedure "D").
5 Select the following menu items: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details (Procedure "E").
6 Check that AFS B1 is Incomplete (Procedure "F").
7 Start the engine and warm it up (Procedure "G").
8 Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) for 3 minutes. However, the vehicle should be driven at a constant speed (Procedure "H").
9 Check the monitor result values on the Techstream by selecting the following menu items: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details / RES RATE B1 S1 and RES RATE B2 S1 (Procedure "I").
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 (Procedure "J").
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 (Procedure "K").
12 Select the following menu items: Powertrain / Engine and ECT / Trouble Codes (Procedure "L").
13 Check if any DTCs are set (Procedure "M").

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM





CONFIRMATION DRIVING PATTERN

This confirmation driving pattern is used in steps 4, 7, 17, and 21 of the following diagnostic troubleshooting procedure when using the Techstream.









1 Connect the Techstream to the DLC3 (Procedure "A").
2 Turn the ignition switch to ON (Procedure "B").
3 Turn the Techstream on (Procedure "C").
4 Clear the DTCs DTC Check / Clear (Procedure "D").
5 Start the engine, and warm it up until the ECT reaches 70°C (158°F) or higher (Procedure "E").
6 Select the following menu items on the Techstream to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut (Procedure "F").
7 Drive the vehicle at between 38 mph (60 km/h) and 75 mph (120 km/h) for at least 10 minutes (Procedure "G").
8 Change the transmission to the 2nd gear (Procedure "H").
9 Drive the vehicle at a proper vehicle speed to perform fuel-cut operation (refer to the following HINT) (Procedure "I").
HINT:
Fuel-cut is performed when the following conditions are met:
- Accelerator pedal is fully released.
- Engine speed is 2,500 rpm or more (fuel injection resumes at 1,000 rpm).

10 Accelerate the vehicle to 40 mph (64 km/h) or more by depressing the accelerator pedal for at least 10 seconds (Procedure "J").
11 Soon after performing procedure "J", release the accelerator pedal for at least 4 seconds without depressing the brake pedal, in order to execute fuel-cut control (Procedure "K").
12 Allow the vehicle to decelerate until the vehicle speed declines to less than 6 mph (10 km/h) (Procedure "L").
13 Repeat procedures from "H" through "K" in this information at least 3 times per driving cycle (Procedure "M").
HINT: Completion of all A/F sensor monitors is required to change the value in TEST RESULT.
CAUTION:
Strictly observe posted speed limits, traffic laws, and road conditions when performing these driving patterns.

INSPECTION PROCEDURE
HINT: Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL 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 A/F CONTROL operation using the Techstream.
1 Connect the Techstream to the DLC3.
2 Start the engine and turn the Techstream on.
3 Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
4 Select the following menu items on the Techstream: 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 Techstream.
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:





NOTICE:
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 the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(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 A3 or A4 A/F sensor connector.
(b) Measure the resistance between the terminals of the A/F sensor connector.
Standard resistance:

Bank 1





Bank 2





(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 A3 or A4 A/F sensor connector.
(b) Turn the ignition switch to 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 E9 ECM connector.
(f) Measure the resistance between the terminals of the A/F sensor connector and ECM connector.
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
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) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
Result:





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





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