P1171

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 (PE). 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, DTC P1171 sets.

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 PE mode.

CONDITIONS FOR SETTING THE DTC
The 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 heated oxygen sensor (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

Steps 1-7:

The number below refers to the step number on the diagnostic table.
5. This step checks to see if the HO2S 1 is operating properly.