GM Service Manual Online
For 1990-2009 cars only

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 P0192: Fuel Rail Pressure (FRP) Sensor Circuit Low Voltage

DTC P0193: Fuel Rail Pressure (FRP) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

5 V Reference Voltage

P0107, P0193, P0237, P0642

P0193

P0193, P0643, P0236

FRP Sensor Signal

P0192

P0193

P0193

Low Reference

--

P0193

P0193, P0236, P0643

Circuit/System Description

The fuel rail pressure (FRP) sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5-volt reference voltage on the 5-volt reference circuit and ground on the reference ground circuit. The ECM receives a varying signal voltage on the signal circuit. The ECM monitors the voltage on the FRP sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low.

Conditions for Running the DTC

    • DTCs P0097, P0098, P0099, P0117, P0118, P0192, P0193, P0627, P0628, P0692 are not set.
    • The ignition is ON or the engine is running.
    •  The DTCs run continuously within the enabling conditions.

Conditions for Setting the DTC

P0192

The ECM detects that the signal circuit voltage is less than 0.3 volt for 1 second.

P0193

The ECM detects that the signal circuit voltage is greater than 4.7 volts for 1 second.

Action Taken When the DTC Sets

    • DTCs P0192 and P0193 are Type B DTCs.
    • A message center or an indicator displays Reduced Engine Power when DTC P0192 or P0193 sets.

Conditions for Clearing the DTC

DTCs P0192 and P0193 are Type B DTCs.

Diagnostic Aids

A poor connection, improper terminal contact, or improper terminal retention at the X145 multi-way harness connector may set DTC P0193.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Component Connector End Views
    •  Inline Harness Connector End Views

Description and Operation

Fuel System Description

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 Verification

  1. Engine idling, observe the Actual Fuel Rail Pressure parameter with a scan tool. The pressure should be approximately 3.5-5.5 Mpa (508-798 psi).
  2. Command an increase and decrease in fuel pressure with a scan tool. Observe the scan tool Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure parameters. The Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure should closely match in all the commanded states.
  3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B47B FRP Sensor.
  2. Ignition OFF, test for less than 2 ohms between the low reference circuit terminal 1 and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
  5. 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 K20 ECM.
    If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  6. Install a 3A fused jumper wire at the signal circuit terminal 2. Toggle the jumper wire between the low reference circuit terminal 1 and the 5-volt reference circuit terminal 3. Verify the scan tool Actual Fuel Rail Pressure toggles between 0.1 MPa and 20.1 MPa.
  7. If the specified parameter does not toggle between the minimum and maximum values, test the signal circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  8. If all circuits test normal, replace the B47B FRP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement
    •  Control Module References for ECM replacement, setup, and programming