P1171

SYSTEM DESCRIPTION
The powertrain control module (PCM) can identify if the vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration. This condition is called a power enrichment mode of operation. If power enrichment is requested during a Closed Loop operation, the PCM will provide more fuel to the engine. Under these conditions, the PCM should detect a rich condition. If the PCM does not detect a rich exhaust at this time, DTC P1171 will set. A plugged fuel filter, or a restricted fuel line can prevent adequate amounts of fuel from being supplied during the power enrichment mode.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0131, P0132, P0133, P0134, or P1133 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.

CONDITIONS FOR SETTING THE DTC
^ The O2S 1 voltage is less than 300 mV for 5 seconds.
^ The engine is in the power enrichment mode.

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 a heavy acceleration.
^ Water or alcohol in the fuel may cause a low O2S 1 voltage during acceleration.
^ Check for an adequate amount of fuel in the fuel tank.
^ When the engine is idling or at steady cruise, the O2S 1 voltage should vary from between approximately 100 mV to 100 mV. During the power enrichment mode, more fuel is needed and O2S 1 voltage should rise above 447 mV.
^ Check for malfunctioning or plugged injectors.

TEST DESCRIPTION

DTC P1171 - Steps 1-6:

The number below refers to the step number on the diagnostic table.
4. This step checks to see if the O2S 1 is operating properly.