P1171

Diagnostic Chart:

SYSTEM DESCRIPTION

The PCM's 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 Closed Loop operation (by heavy acceleration), the PCM will provide more fuel to the engine. Under these conditions the PCM should detect a rich condition. If this rich exhaust is not detected at this time, a DTC P1171 will set. A plugged fuel filter or restricted fuel line can prevent adequate amounts of fuel from being supplied during power enrichment mode.


CONDITIONS FOR SETTING THE DTC

^ DTC's P0131, P0132, P0133 and P0134 not set.

^ Engine is operating in Closed Loop.

^ O2S 1 voltage is less than 300 mV for 5 seconds.

^ Engine is in power enrichment mode.


ACTION TAKEN WHEN THE DTC SETS

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.

^ A history DTC is stored.


CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear after 40 consecutive warm up cycles without a fault.

^ DTC(s) can be cleared by using 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 fuel may cause 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 900 mV. During power enrichment mode, more fuel is needed and O2S 1 voltage should rise above 447 mV.

^ Check for faulty or plugged injector(s).


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored on the scan tool for later reference.

4. This step checks to see if the O2S 1 is operating properly.

6. If no faults have been found at this point and no additional DTC's were set, refer to Diagnostic Aids for additional checks and information.