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P2A01



DTC P2A01

DTC DESCRIPTOR

DTC P2A01
HO2S Circuit Closed Loop (CL) Performance Bank 1 Sensor 2

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






TYPICAL SCAN TOOL DATA






CIRCUIT/SYSTEM DESCRIPTION
The heated oxygen sensor (HO2S) 2 is used for catalyst monitoring. This diagnostic runs once per ignition cycle. This diagnostic consists of 2 tests, a passive test and an intrusive test. During the passive test, if the HO2S 2 voltage transitions below 290 mV and above 685 mV, the DTC will pass for this ignition cycle. If the DTC does not pass during the passive test, the intrusive test will begin. During the intrusive test, the control module will force the air-to-fuel ratio rich and/or lean. The control module then waits for a predicted response from the HO2S. If the HO2S 2 voltage transitions below 290 mV and above 685 mV, the DTC will pass for this ignition cycle.

CONDITIONS FOR RUNNING THE DTC

DTC P2A01 - Passive Test
- DTCs P0030, P0053, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0464, P0496, P1133, P2135 are not set.
- The engine is running for at least 6 seconds.
- The ignition voltage is between 9-18 volts.

DTC P2A01 - Intrusive Test
- DTCs P0030, P0053, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0464, P0496, P1133, P2135 are not set.
- The Engine Run Time parameter is more than 6.5 minutes.
- The ignition voltage is between 9-18 volts.
- The Engine Speed parameter is between 1,000-3,000 RPM.
- The MAF Sensor parameter is between 15-40 g/s.
- The Vehicle Speed parameter is between 32-128 km/h (20-80 mph).
- The exhaust gas recirculation (EGR) flow diagnostic is not active.
- The evaporative emission (EVAP) purge diagnostic is not active.
- The Short Term FT Bank 1 or the Short Term FT Bank 2 parameter is between +3.5 and -3.5 percent.
- The Loop Status parameter is closed.
- The EVAP purge solenoid is greater than 0 percent.

CONDITIONS FOR SETTING THE DTC

DTC P2A01
- The HO2S 2 parameter is between 290-685 mV during the passive test.
- One of the following tests fail:

Lean Intrusive Test
- The engine control module (ECM) detects that the HO2S 2 voltage is more than 290 mV for 11.4 seconds.
- The ECM detects that the HO2S 1 voltage is less than 100 mV.

Rich Intrusive Test
- The ECM detects that the HO2S 2 voltage is less than 685 mV for 11.4 seconds.
- The ECM detects that the HO2S 1 voltage is more than 777 mV.

- This diagnostic runs once per trip.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM VERIFICATION
- Allow the engine to reach operating temperature. With the engine running, observe the affected HO2S parameter with a scan tool.
- The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fueling changes.
- The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to Wide Open and back to Closed after running the engine at 1500 RPM for 30 seconds.
- If any HO2S heater DTCs are set, diagnose those DTCs first.
- The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:
- A silicon contaminated HO2S

NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice.

- Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis. Alcohol/Contaminants-in-Fuel Diagnosis
- Engine oil consumption-Refer to Oil Consumption Diagnosis. Component Tests and General Diagnostics
- Engine coolant consumption-Refer to Loss of Coolant. Loss of Coolant

CIRCUIT/SYSTEM TESTING
1. With the engine running at operating temperature, observe the affected HO2S sensor parameter with a scan tool and manipulate the related wiring and connectors. Manipulation should not affect the parameter.
- If manipulation does affect the parameter, then repair the harness or connector.
2. With the ignition ON, the engine OFF, and the sensor disconnected, measure for approximately 4 mV from the affected HO2S sensor low signal circuit to ground.
- If more than approximately 4 mV, test the affected HO2S sensor low signal circuit for a short to voltage or a faulty control module.
- If less than approximately 4 mV, test the affected HO2S sensor low signal circuit for high resistance or for a faulty control module.
3. With the ignition ON, the engine OFF, and the sensor disconnected, measure for approximately 412 mV from the affected HO2S sensor high signal circuit to ground.
- If more than approximately 412 mV, test the affected HO2S sensor high signal circuit for a short to voltage or a faulty control module.
- If less than approximately 412 mV, test the affected HO2S sensor high signal circuit for a short to ground, high resistance, or for a faulty control module.
4. With the ignition ON, the engine OFF, and the sensor disconnected, install a 3-amp fused jumper between the affected HO2S sensor high signal circuit and the affected HO2S sensor low signal circuit. The affected HO2S parameter should indicate 0 mV.
- If all circuits and connectors test normal and the affected HO2S parameter does not indicate 0 mV, replace the control module.
5. With the ignition ON, the engine OFF, and the sensor disconnected, install a test lamp between the affected HO2S sensor high signal circuit and battery voltage. The affected HO2S parameter should indicate approximately 1106 mV.
- If all circuits and connectors test normal and the affected HO2S parameter does not indicate 1106 mV, replace the control module.
6. If the control module and all circuits test normal, replace the affected HO2S sensor.

REPAIR INSTRUCTIONS

NOTE: Refer to Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice.

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1
- Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2
- Control Module References Verification Tests

REPAIR VERIFICATION
1. Clear the DTCs with a scan tool
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
- If this DTC resets, repeat this procedure.
- If this DTC does not reset but others do, perform those diagnostics.
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