DTC P1171 Fuel System Lean During Acceleration. Buick Century 1996

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1996 🢒 Century 🢒 DTC 🢒 DTC P1171 Fuel System Lean During Acceleration


(1)	Flexible Hose
(2)	Fuel Hose Pinch Point
(3)	Return Line
(4)	Pressure Line
(5)	Bleed Hose
(6)	Fuel Hose Pinch Point
(7)	Fuel Hose Pinch Point
(8)	Fuel Pressure Gauge Kit J 29658-D
(9)	Quick-Connect Adapters

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 Setting the DTC

•	DTCs P0131, P0132, P0133 and P0134 are not set.

•	The engine is operating in a Closed Loop operation.

•	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 PCM will record the operating conditions at the time during which the diagnostic fails. This information will store in the Failure Records buffer.

•	A history DTC stores.

•	The coolant fan turns ON.

Conditions for Clearing the MIL/DTC

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

•	A scan tool can clear the MIL/DTCs.

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 900 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

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

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.

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

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.

DTC P1171-Fuel System Lean During Acceleration

Step	Action	Value(s)	Yes	No
1	Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Are any component related DTC's set?	--	Go to Component DTC table	Go to Step 3
3	Check the vehicle for an adequate amount of fuel. Add fuel to the vehicles fuel tank, if the tank is almost empty. Was it necessary to add fuel?	--	Go to Step 5	Go to Step 4
4	Using the scan tool, observe the O2S 1 voltage while running the engine at the specified temperature and RPM. O2S 1 voltage should vary from the specified voltage and occasionally toggle above the specified voltage. Does the O2S 1 toggle?	75°C - 95°C (167°F - 203°F) 1200 RPM 100-900 mV 447mV	Go to Fuel System Diagnosis	Go to DTC P0134 O2S Circuit Insufficient Activity Sensor 1
5	Using the scan tool, clear the DTC's. Start the engine and idle at normal operating temperature. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text. Does the scan tool indicate that this diagnostic has ran and passed?	--	Go to Step 6	Go to Step 2
6	Check if any additional DTC's are set. Are any DTC's displayed that have not been diagnosed?	--	Go to applicable DTC table	System OK, Refer to Diagnostic Aids