DTC P0641 or P06A6. Chevrolet Chevy Suburban

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2008 🢒 Chevy Suburban - 2WD 🢒 Engine 🢒 Engine Controls and Fuel - Hybrid (HP2) 6.0L (LFA) 🢒 DTC P0641 or P06A6

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0641: 5-Volt Reference Circuit

DTC P06A6: 5-Volt Reference Circuit Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open or High Resistance	Short to Voltage	Signal Performance
5-Volt Reference	P0641	P0641, P06A6	P0641	P06A6
Fuel Rail Pressure (FRP) Sensor Signal	P0192	P0191, P0193	P0193	P0191
Fuel Line Pressure Sensor Low Reference	--	P0641, P06A6	--	P06A6

The fuel pressure sensor is located on the fuel line. The fuel pressure sensor monitors the fuel pressure in the fuel line. The fuel pump flow control module (FPCM) monitors the voltage signal from the fuel pressure sensor.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

•	The FPCM detects that the fuel pressure 5-volt reference is above or below a predetermined voltage threshold.

•	The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

DTCs P0641 and P06A6 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0641 and P06A6 are Type A DTCs.

Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description.
Ignition ON, verify the scan tool hood position parameter displays Open.

⇒	If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.

Ignition OFF, disconnect harness connector of the fuel pressure sensor.
Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the FPCM.

Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the FPCM.

If all circuits test normal, replace the fuel pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Fuel Pressure Sensor Replacement

•	Control Module References for FPCM replacement, setup, and programming