P2270

DTC P2270 or P2272

Circuit Description

The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range. The ECM test for the following conditions:

* The ECM monitors the HO2S voltage to determine if the signal voltage goes above a predetermined threshold within a certain amount of time. If the ECM determines that the signal voltage remains below a threshold, the ECM commands a rich condition. If the signal voltage does not go above the threshold within a certain amount of time after commanding the system rich, this DTC sets.
* The ECM monitors the HO2S voltage during power enrichment. If the ECM determines that the signal voltage is less than a predetermined voltage during power enrichment, this DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

* DTC P2270 HO2S Signal Stuck Lean Bank 1 Sensor 2
* DTC P2272 HO2S Signal Stuck Lean Bank 2 Sensor 2

Conditions for Running the DTC

* Before the ECM can report DTC P2270 or P2272 failed, DTC P0036, P0037, P0038, P0056, P0057, P0058, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, P0393, P0443, P0458, and P0459 must run and pass.
* DTCs P0461, P0462, P0463, P2066, P2067, and P2068 are not set.
* The engine is operating.
* The rear HO2S are at operating temperature for more than 10 seconds.
* The long term fuel control is enabled.
* The mass air flow (MAF) sensor g/s for more than 3 second during the intrusive test.
* DTC P2270 and P2272 runs continuously once the above conditions are met for approximately 10 minutes when the fuel level is more than 12 percent.
* DTC P2270 and P2272 runs continuously once the above conditions are met for approximately 20 minutes when the fuel level is less 12 percent.

Conditions for Setting the DTC

If the ECM detects that the rear HO2S voltage is less than 650 mV for more than 100 seconds, then an intrusive test is performed. The ECM will enrich the fuel mixture up to 30 percent and then wait for 10 seconds at 30 percent. If the ECM detects that the HO2S voltage is still less than 650 mV, this DTC sets.

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) at the beginning of the fourth ignition cycle, after 3 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 and related Freeze Frame data clears after 40 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.

Diagnostic Aids

* Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
* The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views.
* A fuel delivery condition causes this DTC to set. Thoroughly inspect all items that cause a lean condition.
* For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

Test Description

Step 1 - Step 9:

Step 10 - Step 18:

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if a condition exists.
5. This step is testing for a rear HO2S sensor circuit condition. A circuit condition sets this DTC.
8. This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.