Posted on by

Electronic Control System Gas Plus Engines – FAULT CODE 2187

Exhaust Back Pressure – Data Valid but Above Normal Operational Range – Moderately Severe Level

Overview

CODE REASON EFFECT
Fault Code: 2187
PID: S34
SPN: 648
FMI: 0/16
LAMP: Amber
SRT: 

Exhaust Back Pressure – Data Valid but Above Normal Operational Range – Moderately Severe Level. Pressure is above the engine protection limit.

Progressive speed and power derate.

Exhaust Back Pressure Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) uses this sensor’s input to determine the pressure of the exhaust gas, which affects the fueling of the engine.

Component Location

The exhaust back pressure sensor is located above the rocker housing and is attached to the closed-crankcase ventilation filter bracket.

Shop Talk

The arrangement of this sensor allows some condensation/sludge buildup within the tube arrangement. Before replacing the sensor, make sure this tube is free from blockage.

On the L Gas Plus, an original equipment manufacturer (OEM) tube from the exhaust connects to a boiler box on the exhaust side of the engine. A tube then connects the box to the exhaust back pressure sensor.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 2187 active?
STEP 2. Check the exhaust back pressure sensor.  
  STEP 2A. Inspect the exhaust back pressure sensor and engine harness connector pins. Dirty or damaged pins?
  STEP 2B. Check the sensor accuracy. Exhaust back pressure (absolute) read atmospheric pressure?
  STEP 2C. Inspect the back pressure sensing hardware for cracked fittings, plugging, or leaks. Verify back pressure measurement location. Hardware failure or installation issue found?
  STEP 2D. Check the exhaust back pressure. Pressure between 61 to 127 mm Hg [2.4 to 5.0 in Hg]?
STEP 3. Check for excessive oil consumption.  
  STEP 3A. Inspect the closed crankcase ventilation system. Excessive oil, plugging, wrong orientation, or oil carryover?
  STEP 3B. Check for oil residue in the turbocharger compressor outlet plumbing. Oil residue present?
  STEP 3C. Check for oil in the charge air cooler outlet. Oil present?
  STEP 3D. Check for oil residue in the turbocharger turbine outlet. Oil residue present?
  STEP 3E. Inspect the valve stem seals. Damaged, cracked, wrong, or improperly installed valve stem seals?
STEP 4. Check air to fuel ratio control.  
  STEP 4A. Check the overhead set. Valve lash out of specification?
  STEP 4B. Check the gas flow measurement. Excessive compressor oil carryover in the fuel system.
  STEP 4C. Check the fuel mixer housing. Fuel mixer incorrect or venturi sleeve
not seated properly?
  STEP 4D. Check the gas mass flow sensor and fuel control valve. Steady-state gas mass flow compensation > 90 percent and gas mass flow deviation > 4.7 lt/hr [10 lb/hr]?
  STEP 4E. Check for an exhaust system leak. Exhaust leaks?
STEP 5. Check combustion chamber sealing.  
  STEP 5A. Check cylinder leak down. Does cylinder pass leak down test?
STEP 6. Check the exhaust back pressure.  
  STEP 6A. Check the exhaust back pressure. Pressure between 61 to 127 mm Hg [2.4 to 5.0 in Hg]?
STEP 7. Clear the fault codes.  
  STEP 7A. Disable the fault code. Fault Code 2187 inactive?
  STEP 7B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

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

Action

Check the fault codes.

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

Fault Code 2187 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the exhaust back pressure sensor.

Guided Step 2A – Inspect the exhaust back pressure sensor and engine harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine harness from the exhaust back pressure sensor.

Action

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

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

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

Dirty or damaged pins?
YES NO

Us electronic contact cleaner, Part Number 3824510, to flush the dirt, debris, or moisture from the connector pins.

Install the appropriate connector seal if it is damaged or missing.

Repair or replace the engine harness.

Refer to Procedure
019-202 or Procedure
019-043.

Replace the sensor. Refer to Procedure
019-347.

 No Repair

Guided Step 2B – Check the sensor accuracy.

Conditions

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

Action

Verify the sensor accuracy.

  • Use INSITE™ electronic service tool to verify the sensor accuracy.

Note: Convert psia to in. Hg. by multiplying by 2.036.

Exhaust back pressure (absolute) read atmospheric pressure?
YES NO
No Repair

Verify the sensing tube is free of blockage and replace the sensor.

refer to Procedure
019-347.

Guided Step 2C – Inspect the back pressure sensing hardware for cracked fittings, plugging, or leaks. Verify back pressure measurement location.

Conditions

  • Turn keyswitch OFF.

Action

Inspect the sensing hardware and measurement location.

  • Inspect the back pressure sensing hardware for cracked fittings, plugging, or leaks. Verify the back pressure measurement location is correct.

Hardware failure or installation issue found?
YES NO

Repair or replace the failed components, or correct the exhaust back pressure measurement location.

 No Repair

Guided Step 2D – Check the exhaust back pressure.

Conditions

  • Turn keyswitch OFF.

Action

Check the exhaust back pressure.

  • Measure the exhaust restriction.

Refer to Procedure 011-009 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

Make sure the back pressure tube is free from blockage.

Pressure between 61 to 127 mm Hg [2.4 to 5.0 in Hg]?
YES NO
No Repair

Remove the catalyst and utilize piping to restrict to required back pressure.

Guided Step 3 – Check for excessive oil consumption.

Guided Step 3A – Inspect the closed crankcase ventilation system.

Conditions

  • Turn keyswitch OFF.

Action

Check the closed crankcase ventilation system.

  • Check the closed crankcase ventilation canister for excessive oil.
  • Inspect the drain line for plugging and proper orientation of the check valve.
  • Check for excessive oil carryover in the closed crankcase ventilation return line.

Excessive oil, plugging, wrong orientation, or oil carryover?
YES NO

Repair the closed crankcase ventilation system.

 No Repair

Guided Step 3B – Check for oil residue in the turbocharger compressor outlet plumbing.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the turbocharger outlet pipe.

Action

Check for oil residue.

  • Check for oil residue in the turbocharger compressor outlet plumbing.

Oil residue present?
YES NO

The turbocharger is the source of the oil. Replace the turbocharger.

Refer to Procedure 010-033 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 3C – Check for oil in the charge air cooler outlet.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the charge air cooler outlet pipe.

Action

Check the charge air cooler.

  • Check for oil in the charge air cooler outlet.

Oil present?
YES NO

Clean the charge air cooler.

Remove and clean the intake piping.

Refer to Procedure 010-027 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 3D – Check for oil residue in the turbocharger turbine outlet.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the turbocharger turbine piping.

Action

Check the turbocharger turbine outlet.

  • Check for oil residue in the turbocharger turbine outlet.

Oil residue present?
YES NO

The turbocharger is the source of the oil. Replace the turbocharger.

Refer to Procedure 010-033 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

Replace the oxygen sensor.

Refer to Procedure
019-100.

Clean the exhaust system of any oil or residue.

 No Repair

Guided Step 3E – Inspect the valve stem seals.

Conditions

  • Turn keyswitch OFF.

Action

Remove the valve covers.

  • Inspect the valve stem seals.

Damaged, cracked, wrong, or improperly installed valve stem seals?
YES NO

Replace the valve stem seals. Clean the exhaust system of any oil or residue.

Refer to the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 4 – Check air to fuel ratio control.

Guided Step 4A – Check the overhead set.

Conditions

  • Turn keyswitch OFF.

Action

Remove the valve cover.

  • Check the overhead set. Refer to the Procedure 003-004 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
    3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
    3666164.

Valve lash out of specification?
YES NO

Adjust the overhead.

Refer to Procedure 003-004 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 4B – Check the gas flow measurement.

Conditions

  • Turn keyswitch OFF.

Action

Check the gas flow measurement.

  • Remove the fuel system components downstream of the fuel filter and check for excessive compressor oil carryover in the fuel system.

Excessive compressor oil carryover in the fuel system?
YES NO

Replace the fuel system screen pack and the gas mass flow sensor.

Refer to Procedure
019-101.

Clean the fuel system of compressor oil contamination.

Be sure the fuel filter drain interval is in accordance with the maintenance schedule.

 No Repair

Guided Step 4C – Check the fuel mixer housing.

Conditions

  • Turn keyswitch OFF.

Action

Verify that the fuel shutoff valve (or plug on B LPG Plus) is installed properly and check for debris on the screen.

B Gas Plus and B LPG Plus:

  • Verify the mixer set screws are in place and the mixer is oriented properly. Check for oil or debris on the gas mass flow sensor screen.

C Gas Plus and L Gas Plus

  • Verify the o-ring sealing, snap ring is installed, the mixer part number and orientation are correct, and the set screw is properly installed behind the gas mass flow sensor to hold the flow venturi in place.

Fuel mixer incorrect or venturi sleeve
not seated properly?
YES NO

Replace or repair the fuel mixer.

Refer to the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 4D – Check the gas mass flow sensor and fuel control valve.

Conditions

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

Action

Check the gas mass flow sensor and fuel control valve.

Automatic Transmission:

  • Use INSITE™ electronic service tool to perform a Stall Test.

Manual Transmission:

  • Do a road test including operation at rated power.

Check for the following:

  • Steady-state gas mass flow compensation > 90 percent
  • Gas mass flow deviation > 4.7 lt/hr [10 lb/hr].

Steady-state gas mass flow compensation > 90 percent and gas mass flow deviation > 4.7 lt/hr [10 lb/hr]?
YES NO

Be sure voltage regulation is installed as appropriate.

Replace the gas mass flow sensor or replace the fuel control valve.

Refer to Procedure
019-101 or to the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 4E – Check for an exhaust system leak.

Conditions

  • Turn keyswitch ON.
  • Engine running.

Action

Check for exhaust leaks.

  • Check for exhaust leaks at the turbocharger gasket, exhaust manifold gasket leaks, or leak upstream of the oxygen sensor in the exhaust stack.

Exhaust leaks?
YES NO

Repair or replace the leaking components.

Refer to the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

 No Repair

Guided Step 5 – Check combustion chamber sealing.

Guided Step 5A – Check cylinder leak down.

Conditions

  • Turn keyswitch OFF.

Action

Check the engine compression.

  • Refer to Procedure 014-012 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
    3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
    3666164.

Does cylinder pass leak down test?
YES NO
No Repair

Repair the engine as necessary.

Refer to the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
3666164.

Guided Step 6 – Check the exhaust back pressure.

Guided Step 6A – Check the exhaust back pressure.

Conditions

  • Turn keyswitch OFF
  • Remove the test piece installed in Step 2D.
  • Install the original catalyst.

Action

Check the exhaust back pressure.

  • Check the exhaust restriction. Refer to Procedure 011-009 in the Troubleshooting and Repair Manual, C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin
    3666206, or Troubleshooting and Repair Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin
    3666164.
  • Make sure the back pressure tube is free from blockage.

Pressure between 61 to 127 mm Hg [2.4 to 5.0 in Hg]?
YES NO
No Repair

Inspect the oxidation catalyst and/or muffler, and replace according to the manufacturer’s instructions.

Guided Step 7 – Clear the fault codes.

Guided Step 7A – 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 1 minute.
  • Use INSITE™ electronic service tool to verify that Fault Code 2187 is inactive.

Fault Code 2187 inactive?
YES NO
No Repair

Return to the troubleshooting steps or contact a Cummins Authorized Repair Location if all steps have been completed and checked again.

Guided Step 7B – Clear the inactive fault codes.

Conditions

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

Action

Clear the inactive fault codes.

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

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  01-Apr-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.