DTC P2A00 A/F Sensor Slow Response (Sensor 1 Bank 1)
NOTE:
Sensor 1 indicates the sensor located at the front of the three-way catalytic converter (TWC) near the engine.
P2A00.Description
| No. DTC | DTC detection condition | Faulty plot |
| P2A00 | Calculated wear value based on air-fuel ratio (A/F) sensor response time below threshold value (2 trip diagnostic logic) |
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P2A00.Monitor description
After the engine warms up, the ECM provides feedback on the air-fuel ratio to maintain near stoichiometric levels.In addition, after the necessary conditions are met, the air-fuel ratio is actively controlled for approximately 10 seconds to measure the response time of the A/F sensor.During active air-fuel ratio control, the ECM forcibly raises and lowers the fuel injection amount by a certain amount based on the stoichiometric ratio calculated during normal air-fuel ratio control, and measures the response time of the A/F sensor.During active air-fuel ratio control, the ECM receives the A/F sensor signal and uses it to calculate the amount of wear based on the response time of the A/F sensor.
If the A/F sensor's wear response time is below the threshold, the ECM interprets this as a malfunction and logs a DTC.
P2A00.Driving in test mode
NOTE:
Driving in test mode activates A/F sensor response time monitoring.
(a) Connect the handheld diagnostic tool to the DLC3 connector.- (b) Turn on the ignition (IG).
- (c) Turn on the portable diagnostic tool.
- (d) Clear DTCs (if equipped) .
- (e) Select the following menu items: Powertrain / Engine and ECT / Data List / Monitor Status.
- (f) Verify that "O2S(A/FS) Monitor" is set to "Incmpl."(not completed).
- (g) Start and warm up the engine.
- (h) Drive the vehicle at 25-75 mph (40-120 km/h) for 3 minutes.
- (i) Verify that "O2S(A/FS) Monitor" is set to "Compl."(completed).
- (j) Select the following menus: Powertrain / Engine and ECT / DTC.
- (k) Check if any DTCs are output (any pending DTCs).
P2A00.Connection diagram
P2A00.Check sequence
NOTE:
Only when using the portable diagnostic tool:
By performing the "Control the Injection Volume for A/F Sensor" test in Active Test mode, the problem area can be identified.The "Control the Injection Volume for A/F Sensor" test can help determine which component is at fault: the air fuel ratio (A/F) sensor, the heated oxygen sensor (HO2), or some other potentially faulty component.
The following instructions describe how to perform the "Control the Injection Volume for A/F Sensor" test using the handheld diagnostic tool.
- (a) Connect the handheld diagnostic tool to the DLC3 connector.
- (b) Start the engine and turn on the handheld diagnostic tool.
- (c) Warm up the engine at 2500 rpm for approximately 90 seconds.
- (d) On the handheld diagnostic tool, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
- (e) Perform "Control the Injection Volume for A/F Sensor" test with engine idling (press right or left button to change fuel injection volume).
- (f) Monitor the output voltage of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2) displayed on the scan tool display.
NOTE:
- During the "Control the Injection Volume for A/F Sensor" test, the fuel injection volume is reduced by 12.5% or increased by 25%.
- Each sensor must respond appropriately to an increase or decrease in fuel injection volume.
Rated value / Rated mode:
Information on the instrument display
(Sensor)Fuel injection volume State Voltage AFS B1 S1
(A/F)+25% Enrichment Less than 3.0 -12.5% Impoverishment Over 3.35 O2S B1 S2
(HO2)+25% Enrichment More than 0.5 -12.5% Impoverishment Less than 0.4
NOTE:
The A/F sensor output delay is a few seconds and the HO2 output delay is approximately 20 seconds.
| Frame | Air fuel ratio sensor (sensor 1) Output voltage |
HO2 sensor (sensor 2) Output voltage |
Most likely location of the fault | ||
| one | Fuel injection volume +25% -12.5% |
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Fuel injection volume +25% -12.5% |
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| Output voltage more than 3.35V less than 3.0V |
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Output voltage more than 0.5V less than 0.4V |
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| 2 | Fuel injection volume +25% -12.5% |
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Fuel injection volume +25% -12.5% |
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| Output voltageAlmost no response |
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Output voltage more than 0.5V less than 0.4V |
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| 3 | Fuel injection volume +25% -12.5% |
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Fuel injection volume +25% -12.5% |
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| Output voltage more than 3.35V less than 3.0V |
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Output voltageAlmost no response |
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| 4 | Fuel injection volume +25% -12.5% |
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Fuel injection volume +25% -12.5% |
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| Output voltageAlmost no response |
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Output voltageAlmost no response |
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- The "Control the Injection Volume for A/F Sensor" test described below allows the mechanic to measure and plot the output voltage for the A/F and HO2 sensors.
- To display the graph on the handheld diagnostic tool, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Enter / View / AFS B1 S1 and O2S B1 S2.
NOTE:
- DTC P2A00 may also be set if the air-fuel ratio is constantly rich or constantly lean.
- A low voltage at the output of the A/F sensor may be due to a rich air-fuel mixture.Check for conditions that cause the engine to run rich.
- A high voltage at the output of the A/F sensor may be caused by a lean air-fuel mixture.Check for conditions that caused the engine to run lean.
- Read the fixed parameters using the portable diagnostic tool.These parameters reflect the state of the engine at the time the fault was detected.When troubleshooting, fixed parameters allow you to determine whether the car was moving at the time of the malfunction or not, whether the engine was warm, what was the air-fuel mixture (lean or rich), etc.
| 1.CHECK FOR OTHER DTCs (OTHER THAN DTC P2A00) |
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Connect the handheld diagnostic tool to the DLC3.
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Turn on the ignition (IG).
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Turn on the portable diagnostic tool.
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Select the following menu items: Powertrain / Engine and ECT / DTC.
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Read DTCs.
Result:
Indication (displayed DTCs) Next step P2A00 BUT P2A00 and other DTCs B
If any A/F sensor related DTCs (DTCs for A/F sensor heater conductivity or A/F sensor heater conduction) are logged, troubleshoot those DTCs first.
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| BUT | |
| 2.CHECK AIR FUEL RATIO SENSOR (HEATER RESISTANCE) |
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Disconnect the B7 A/F sensor connector.
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Measure the resistance of the A/F sensor connector.
Rated resistance:
Contacts for connecting a diagnostic tool Given conditions HA1A (1) - +B (2) 1.8-3.4 ohms at 20°C (68°F) HA1A(1)-A1A-(4) 10 kΩ or more
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Connect the A/F sensor connector.
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| OK | |
| 3.CHECK HARNESS AND CONNECTOR (ECM - AIR-FUEL RATIO SENSOR) |
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Disconnect the B7 A/F sensor connector.
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Turn on the ignition (IG).
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Measure the voltage between the +B A/F sensor connector and ground.
Rated voltage:
Contacts for connecting a diagnostic tool Given conditions +B (B7-2) - mass 9-14 V
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Switch off the ignition.
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Disconnect the B32 ECM connector.
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Measure resistance.
Rated resistance (check for continuity):
Contacts for connecting a diagnostic tool Given conditions HA1A (B7-1) - HA1A (B32-109) Less than 1 ohm A1A+ (B7-3) - A1A+ (B32-112) Less than 1 ohm A1A- (B7-4) - A1A- (B32-113) Less than 1 ohm Rated resistance (check for short circuit):
Contacts for connecting a diagnostic tool Given conditions HA1A (B7-1) or HA1A (B32-109) - mass 10 kΩ or more A1A+ (B7-3) or A1A+ (B32-112) - Ground 10 kΩ or more A1A- (B7-4) or A1A- (B32-113) - Mass 10 kΩ or more
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Connect the ECM connector.
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Connect the A/F sensor connector.
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| OK | |
| 4. RIDE IN TEST MODE |
| FURTHER | |
| 5.CHECK IF DTC OUTPUT RECURS (DTC P2A00) |
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Connect the handheld diagnostic tool to the DLC3.
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Switch on the ignition (IG) and turn on the test tool.
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Select the following menu items: Powertrain / Engine and ECT / DTC.
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Read pending DTCs.
Result:
Indication (displayed DTCs) Next step P2A00 BUT Not displayed B
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| BUT | |
| 6.REPLACE AIR-FUEL RATIO SENSOR |
| FURTHER | |
| 7. RIDE IN TEST MODE |
| FURTHER | |
| 8.CHECK IF DTC OUTPUT RECURS (DTC P2A00) |
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Connect the handheld diagnostic tool to the DLC3.
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Switch on the ignition (IG) and turn on the test tool.
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Select the following menu items: Powertrain / Engine and ECT / DTC.
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Read pending DTCs.
Result:
Indication (displayed DTCs) Next step Not displayed BUT P2A00 B
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| BUT | |
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