Circuit Description
The secondary air injection (AIR) pump system is designed to lower exhaust emission levels after a start up. The AIR pump is timed to remain ON for approximately 1 minute after the engine is started.
The powertrain control module (PCM) commands the AIR pump relay ON by supplying a ground to the AIR pump relay control circuit. This action energizes the AIR pump, forcing fresh air into the exhaust stream. The PCM also commands the AIR vacuum control solenoid ON which applies engine vacuum to the AIR shut-off valve. With vacuum applied to the AIR shut-off valve, airflow from the AIR pump flows through the pipes/hoses to the exhaust check valves, then enters into the exhaust stream. The air, oxygen, that is introduced into the exhaust system accelerates catalyst operation. When inactive, the check valves and the shut-off valve prevent air flow in either direction.
The PCM detects a system air flow condition by monitoring the heated oxygen sensors (HO2S) and Short Term Fuel Trim during normal Open Loop AIR system operation. This is called a passive test. If the passive test indicates a pass, the PCM takes no further action. If the passive test fails or is inconclusive, the diagnostic will proceed with an intrusive or active test. The PCM will command the AIR system ON during Closed Loop operation under normal operating conditions. The active test will pass or fail based on the response from the HO2S. A lean HO2S response indicates that the AIR system is functioning normally. An increasing Short Term Fuel Trim value also indicates a normal functioning system. The AIR diagnostic consists of the passive test and the active tests. The AIR diagnostic requires failure of the passive and active tests on 2 consecutive key cycles to illuminate the malfunction indicator lamp (MIL) and stores a DTC. If the PCM detects that the HO2S and Short Term Fuel Trim did not respond as expected on one of the engine banks, DTC P1415 or P1416 sets.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0151, P0154, P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0300, P0335, P0336, P0351, P0352, P0353, P0354, P0355, P0356, P0357, P0358, P0440, P0442, P0443, P0446, P0449, P1120, P1133, P1134, P1153, P1154, P1220, P1221, P1258, P1441 are not set. |
| • | The engine is running for more than 30 seconds. |
| • | The mass air flow (MAF) is less than 23 g/s. |
| • | The air/fuel ratio is 14.7:1. |
| • | The engine load is less than 40 percent. |
| • | The ignition voltage is more than 11.7 volts. |
| • | The engine is not operating in the Power Enrichment, the Decel Fuel Shut-off, or the Catalyst Over-Temperature Modes. |
| • | The engine speed is more than 850 RPM. |
| • | The engine coolant temperature (ECT) is between -10 and +110°C (14-230°F) . |
| • | The intake air temperature (IAT) is between -10 and +100°C (14-212°F) . |
| • | The fuel system is operating in fuel trim cells 1, 2, 4, 5, or 6. |
Conditions for Setting the DTC
The HO2S voltage does not decrease to less than 222 mV for 1.3 seconds.
OR
The short-term fuel trim does not change more than a predetermined value.
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. |
Diagnostic Aids
| • | For any test that requires probing the PCM or probing a component harness connector, use the J 35616 connector test adapter kit . Using this kit prevents damage to the harness or component terminals. Refer to Using Connector Test Adapters in Wiring Systems. |
| • | Carbon build-up in the exhaust manifold may restrict the amount of air flow necessary to affect the HO2S voltage. If you suspect this condition, remove the air pipe from the manifold and inspect the passage. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
| • | Inspect for the following conditions: |
| - | Excessive exhaust system back pressure |
| - | Moisture, water, or debris ingestion into the AIR pump |
| - | Leaking check valves will leave traces of exhaust carbon in the AIR system. |
| - | A vacuum solenoid leaking vacuum will hold the shut-off valve open an exhaust noise may be heard through the air cleaner fuel trims at idle may be higher than normal a DTC may not set. |
| - | The vacuum lines at the vacuum solenoid cannot be reversed. |
| - | A check valve that flows in both directions causes heat damage to the AIR system components. |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Does the HO2S voltage decrease to less than the specified value? | 222 mV | Go to Diagnostic Aids | Go to Step 3 | ||||||
3 | Perform a visual inspection of all pipes/hoses in the AIR system for the following conditions:
Did you find and correct a condition? | -- | Go to Step 7 | Go to Step 4 | ||||||
4 |
Is air flow present at the hose outlet? | -- | Go to Step 6 | Go to Step 5 | ||||||
5 | Repair the restriction or the leak for the applicable bank in the AIR crossover pipes/hoses between the exhaust check valve and the AIR shut-off valve. Did you complete the repair? | -- | Go to Step 7 | -- | ||||||
6 |
Caution: Refer to Hot Exhaust System Caution in the Preface section. Repair the restriction/leak or blockage for the applicable bank in one of the following components:
Did you find and correct a condition? | -- | Go to Step 7 | -- | ||||||
7 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 8 | ||||||
8 | Observe the Capture Info with a scan tool. Are there any DTCs that you have not yet diagnosed? | -- | System OK | |||||||
