Posted on by

Electronic Control System Gas Plus Engines – FAULT CODE 449

Fuel Pressure Sensor – Over Pressure Warning

Overview

CODE REASON EFFECT
Fault Code: 449
PID: P94
SPN: 94
FMI: 0/16
LAMP: Amber
SRT: 

Fuel Pressure Sensor – Over Pressure Warning. Fuel pressure signal indicates that fuel pressure has exceeded the maximum limit for the given engine condition.

Possible erratic engine performance.

Fuel Pressure/Temperature Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) uses the fuel pressure/temperature sensor (combination sensor) to measure the fuel temperature, as well as secondary pressure.

Component Location

The fuel pressure/temperature sensor is located in the fuel housing.

Shop Talk

The fuel pressure/temperature sensor measures the secondary fuel pressure to the engine. This is after the low-pressure regulator. The fuel pressure/temperature sensor, secondary, is an absolute sensor.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for multiple fault codes. Fault Codes 118, 119, 2118, 2119, and/or 2228 active?
  STEP 1B. Check the fuel pressure at the low-pressure regulator. Is pressure less than maximum value for the engine family?
  STEP 1C. Check the fuel pressure at the high-pressure regulator. Is pressure less than maximum value for the engine family?
STEP 2. Check the secondary fuel pressure sensor.  
  STEP 2A. Inspect the secondary fuel pressure sensor and engine harness connector pins. Dirty or damaged pins?
  STEP 2B. Verify the fuel pressure sensor reading. Fuel pressure measurement within 5 percent?
STEP 3. Clear the fault codes.  
  STEP 3A. Disable the fault codes. Fault Coed 449 inactive?
  STEP 3B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Check for multiple fault codes.

Conditions

  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

Read the fault codes.

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Codes 118, 119, 2118, 2119, and/or 2228 active?
YES NO

Troubleshoot the active fault codes. If all fault codes are active, start by troubleshooting Fault Code 2228.

 No Repair
Appropriate troubleshooting tree

Guided Step 1B – Check the fuel pressure at the low-pressure regulator.

Conditions

  • Turn keyswitch ON.

Action

Check the fuel pressure after the low-pressure regulator.

  • Refer to Procedure
    005-047 in the C8.3G (Natural Gas) Engines, Troubleshooting and Repair Manual, Bulletin 3666206 or Procedure
    005-047 in the B5.9G, B5.9LPG, B Gas Plus and B LPG Plus Troubleshooting and Repair Manual, Bulletin 3666164.

Maximum pressures:

  • B, C and L Gas Plus – 655 kPa [95 psia].
  • B LPG Plus – 483 kPa [70 psia].

Is pressure less than maximum value for the engine family?
YES NO
No Repair No Repair

Guided Step 1C – Check the fuel pressure at the high-pressure regulator.

Conditions

  • Turn keyswitch ON.

Action

Check the fuel pressure before the low pressure regulator.

  • Refer to Procedure
    005-061 in the C8.3G (Natural Gas) Engines, Troubleshooting and Repair Manual, Bulletin 3666206 or Procedure
    005-061 in the B5.9G, B5.9LPG, B Gas Plus and B LPG Plus Troubleshooting and Repair Manual, Bulletin 3666164.

Maximum pressures:

  • B, C and L Gas Plus – 12.8 bar [185 psia].
  • B LPG Plus – 21.7 bar [315 psia].

Is pressure less than maximum value for the engine family?
YES NO

Replace the low pressure regulator. Refer to Procedure
005-047 in the C8.3G (Natural Gas) Engines, Troubleshooting and Repair Manual, Bulletin 3666206 or Procedure
005-047 in the B5.9G, B5.9LPG, B Gas Plus and B LPG Plus Troubleshooting and Repair Manual, Bulletin 3666164.

Replace the high pressure regulator. Refer to the OEM troubleshooting and repair manual.

Guided Step 2 – Check the secondary fuel pressure sensor.

Guided Step 2A – Inspect the secondary fuel pressure sensor and engine harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness from the secondary fuel pressure sensor.

Action

Inspect the sensor and engine harness connector pins for the following:

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damaged
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Connector shell broken
  • Dirt or debris in or on the connector pins.

Refer to the circuit diagram or wiring diagram for component pin identification.

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure
019-361.

Dirty or damaged pins?
YES NO

Repair the damaged pins. Repair or replace the engine harness, or replace the sensor, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure
    019-202.
  • Replace the engine harness. Refer to Procedure
    019-043.
  • Replace the sensor. Refer to Procedure
    019-153.
 No Repair

Guided Step 2B – Verify the fuel pressure sensor reading.

Conditions

  • Install a mechanical pressure gauge
  • Turn keyswitch on
  • Connect INSITE™ electronic service tool.

Action

Verify the fuel pressure reading.

  • Use INSITE™ electronic service tool to verify the fuel pressure measurement against the fuel pressure measurement value displayed on the mechanical gauge.

Fuel pressure measurements within 5 percent?
YES NO
No Repair

Replace the sensor. Refer to Procedure
019-188.

Guided Step 3 – Clear the fault codes.

Guided Step 3A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

Disable the fault code.

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to verify that Fault Code 449 is inactive.

Fault Code 449 inactive?
YES NO
No Repair No Repair

Guided Step 3B – Clear the inactive fault codes.

Conditions

  • Connect all components.
  • Turn keyswitch ON.

Action

Clear the inactive fault codes.

  • Erase the inactive fault codes using INSITE™.

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  04-Dec-2009
Avatar photo

Published by Jack

Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.