P2A00
DTC P2A00
CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference, or bias, voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once the sensor reaches operating temperature. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature and provide an accurate voltage signal. If the PCM detects an active HO2S 1 signal of a lower than calibrated minimum amplitude, DTC P2A00 will set for bank 1 sensor 1.
Each HO2S 1 has the following circuits:
- The HO2S 1 high signal circuit
- The HO2S 1 low signal circuit
- The HO2S 1 ignition 1 voltage circuit
- The HO2S 1 heater low control circuit
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P2A00 HO2S Circuit Closed Loop (CL) Performance Bank 1 Sensor 1
CONDITIONS FOR RUNNING THE DTC
- 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, P1134, P2135 are not set.
- The Engine Run Time parameter is at least 3 minutes.
- The traction control, if equipped, is not active.
- The PCM is not commanding Power Enrichment or Decel Fuel Cutoff modes.
- The MAF Sensor parameter is between 5-38 g/s.
- The Engine Speed parameter is between 602-3,000 RPM.
- The TP Indicated Angle parameter is between 3-35 percent.
- The ECT Sensor parameter is more than 65°C (149°F).
- The system voltage is between 9-18 volts.
- The above conditions have been met for 3 seconds.
CONDITIONS FOR SETTING THE DTC
- The PCM detects that the HO2S 1 voltage signal remains within the 300-600 mV range for more than 3.6 seconds.
- This diagnostic runs continuously.
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.
TEST
