A secondary air injection (AIR) pump is used on this vehicle in order to lower tailpipe emissions on start-up. The VCM supplies a ground to the AIR pump relay control circuit. This energizes the AIR pump relay and supplies voltage to the AIR pump clutch. The VCM uses the HO2S voltages and the short term fuel trim in order to diagnose the secondary air injection system.
The VCM monitors the HO2S voltages and the short term fuel trim value when the AIR pump is energized. This additional air causes the HO2S voltages to shift low, reflecting the leaner mixture. The short term fuel trim should increase above 128 confirming that the VCM is supplying additional fuel. The low HO2S voltages and higher short term fuel trim value provide confirmation that the secondary air injection system is operating properly. When the AIR pump is de-energized, the HO2S voltages should increase and begin switching normally.
If only one HO2S responded as expected, the VCM sets either a DTC P1415 or P1416 depending on which engine bank the AIR system is inoperative.
• | No active ECT sensor DTCs |
• | No active IAC sensor DTCs |
• | No active heated oxygen sensor DTCs |
• | No active misfire DTCs |
• | No active MAP sensor DTCs |
• | No active fuel trim DTCs |
• | No active EVAP system DTCs |
• | No active TP sensor DTCs |
• | No active IAT sensor DTCs |
• | No active MAF sensor DTCs |
• | The system voltage is more than 10 volts. |
• | The IAT is more than 0°C (32°F). |
• | The power enrichment mode is not active. |
• | Decel fuel cut-off not active |
• | The commanded air/fuel ratio is 14.7:1. |
• | The engine speed is more than 550 RPM. |
• | The engine load is less than 50 percent. |
• | The MAF is less than 100 g/s. |
• | The ECT is between 75°C and 105°C (167°F to 221°F). |
• | The system has been in closed loop mode for more than 15 seconds. |
The VCM has not detected a change in HO2S voltage and short term fuel trim when the secondary air injection pump is energized.
The VCM will turn ON the malfunction indicator lamp (MIL) after two consecutive test cycles with the fault active.
• | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
• | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
• | Use a scan tool in order to clear the DTCs. |
Intermittent conditions can be caused by wiring problems.
An intermittent may be caused by any of the following conditions:
• | A poor connection |
• | Rubbed through wire insulation |
• | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the cause of the DTC is still present.
This step determines if there is a problem before or after the check valve.
Step | Action | Values | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |||||||||||
Does the Short Term Fuel Trim Bank 1 indicate a change of more than the specified value within 30 seconds? | 20 % | Go to Step 3 | Go to Step 4 | |||||||||||
3 | The DTC is intermittent. Are any additional DTCs stored? | -- | Go to the applicable DTC table | Go to Diagnostic Aids | ||||||||||
4 | Inspect the AIR System Bank 1 for the following:
Did you find a problem? | -- | Go to Step 8 | Go to Step 5 | ||||||||||
Does air flow from the hose? | -- | Go to Step 6 | Go to Step 7 | |||||||||||
6 | Inspect for restrictions or leaks in the check valve and the AIR pipe on Bank 1. Did you find a problem? | -- | Go to Step 8 | Go to Diagnostic Aids | ||||||||||
7 | Inspect for restrictions or leaks in the Bank 1 AIR hose between the AIR shut off valve and the check valve. Did you find a problem? | -- | Go to Step 8 | |||||||||||
8 | Repair as necessary. Refer to Secondary Air Injection Check Valve and Check Valve Pipe Replacement . Is the action complete? | -- | Go to Step 9 | -- | ||||||||||
9 |
Does the scan tool indicate the diagnostic Passed? | -- | Go to Step 10 | Go to Step 2 | ||||||||||
10 | Using the scan tool, select Capture Info, Review Info. Are any additional DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |