DTC P1171 Fuel System Lean During Acceleration. Oldsmobile Alero 2000

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 2000 🢒 Alero 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 DTC P1171 Fuel System Lean During Acceleration

Refer to

Fuel System with Fuel Pressure Gauge Kit


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

in Engine Controls Component Views.

System Description

The internal circuitry of the Powertrain Control Module (PCM) 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, 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, DTC P1171 will set.

Conditions for Running the DTC

•	The following DTCs are not set: P0131, P0132, P0133 P0134 and P1133.

•	The engine coolant temperature (ECT) is more than 20°C (70°F).

•	The engine has been running for more than 20 seconds.

•	The engine is operating in Closed Loop mode.

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 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.

•	Use a scan tool to clear the DTCs.

Diagnostic Aids

•	A restricted fuel filter can not supply adequate fuel during heavy acceleration.

•	Any water or alcohol in the fuel may cause a low O2S 1 voltage during acceleration.

•	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.

•	Test for malfunctioning or plugged fuel injectors.

Test Description

The number below refers to the step number on the diagnostic table.

This step tests the O2S 1 for correct operation.

DTC P1171-Fuel System Lean During Acceleration

Step	Action	Values	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Operate the vehicle within the Freeze Frame conditions and the Conditions for Running the DTC as specified in the supporting text. Did the DTC reset?	--	Go to Step 3	Go to Diagnostic Aids
3	Inspect the vehicle for adequate fuel. Add fuel if the fuel tank is almost empty. Did you add fuel?	--	Go to Step 5	Go to Step 4
4	Start the engine and run the engine at the specified temperature and RPM. Use a scan tool in order to observe the O2S 1 voltage. The O2S 1 voltage should vary within the specified range and occasionally toggle above the high voltage. Does the O2S 1 voltage toggle above the high end of the specified range?	75°C - 95°C (167°F - 203°F) 1,200 RPM 100 - 900 mV	Go to Fuel System Diagnosis	Go to DTC P0134 O2S Circuit Insufficient Activity Sensor 1
5	Use a scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	--	Go to Step 2	System OK