System Description
The powertrain control module (PCM) internal circuitry can identify if the vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration (power enrichment). When a power enrichment mode of operation is requested during a Closed Loop operation, by heavy acceleration, the PCM provides additional fuel to the engine. Under these conditions the PCM should detect a rich condition. Whenever this rich exhaust is not detected, a DTC P1171 sets. A plugged fuel filter or restricted fuel line can prevent adequate amounts of fuel from being supplied during Power Enrichment Mode.
Conditions for Running the DTC
| • | DTCs P0122, P0123, P0131, P0132, P0133, or P0134 are not set. |
| • | The engine coolant temperature (ECT) is more than 20°C (70°F). |
| • | The engine has been running for longer than 20 seconds. |
| • | The engine is operating in a Closed Loop operation. |
| • | The engine is in the power enrichment mode. |
Conditions for Setting the DTC
The heated oxygen sensor (HO2S) 1 voltage is less than 300 mV for 10 seconds.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
| • | A restricted fuel filter can supply adequate amounts of fuel at idle, but may not be able to supply enough fuel during heavy acceleration. Water or alcohol in the fuel may cause low HO2S 1 voltage during acceleration. |
| • | High resistance in the ignition coil control circuits may cause this condition. |
| • | Manifold absolute pressure (MAP) sensor--High resistance in the MAP sensor circuits may cause this condition. |
| • | Check for faulty or plugged fuel injectors. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Are any component related DTCs set? | -- | Go to Step 3 | |
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Was it necessary to add fuel? | -- | Go to Step 6 | Go to Step 5 |
Does the scan tool indicate HO2S 1 voltage varying outside the specified values? | 350-550 mV | Go to Fuel System Diagnosis | Go to DTC P0134 | |
6 |
Does the DTC run and pass? | -- | Go to Step 7 | Go to Step 2 |
7 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
