DTC P1171 Fuel System Lean During Acceleration. GMC Truck Sonoma Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 4WD 🢒 DTC 🢒 DTC P1171 Fuel System Lean During Acceleration

Refer to Engine Controls Component Views
Object Number: 174166 Size: MF


(1)	Fuel Pressure Regulator
(2)	Fuel Shut Off Adapter J 37287
(3)	Fuel Return Line
(4)	Quick Connect Adapter
(5)	Fuel Pressure Pinch Point
(6)	Fuel Pressure Pinch Point
(7)	Fuel Pressure Gauge Kit J 29658-D
(8)	Fuel Filter
(9)	Fuel Pressure Line

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). 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, a DTC P1171 sets.

Conditions for Running the DTC

•	No active oxygen sensor DTCs

•	The engine coolant temperature 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 PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers stores this information.

•	A history DTC is stored.

Conditions for Clearing the DTC

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

•	Use a scan tool to clear the DTCs.

Diagnostic Aids

•	A restricted fuel filter or restricted fuel line 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 O2S 1 voltage during acceleration.

•	Inspect for faulty or plugged fuel injectors.

Test Description

The numbers below refers to the step numbers on the diagnostic table:

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

If no malfunctions are present at this point and no additional DTCs were set, refer to the Diagnostic Aids for additional checks and information.

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	Are any component related DTCs set?	--	Go to Diagnostic Trouble Code (DTC) List/Type	Go to Step 3
3	Inspect the vehicle for an adequate amount of fuel in the fuel tank. Add fuel if the tank is almost empty. Was it necessary to add fuel?	--	Go to Step 5	Go to Step 4
4	Start the engine. Run the engine at the specified temperature and RPM. With the scan tool, observe the O2S 1 voltage. The O2S 1 voltage should vary between the specified voltage and occasionally toggle above the high voltage. Does the O2S 1 toggle above the high voltage?	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 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