Skip to content
| M-F 9AM - 7:30PM EST | SAME-DAY SHIPPING | +1 (877) 795-0656 |
| M-F 9AM - 7:30PM EST | +1 (877) 795-0656 | LIVE CHAT |

How to inspect, diagnose and replace a EGR cooler

Inspecting, diagnosing, and replacing an EGR (Exhaust Gas Recirculation) cooler on diesel engines like Cummins, Paccar, Detroit Diesel, Volvo, or Mack requires expertise, specialized tools, and knowledge of the specific engine model. Here is a general overview of the process, but it is highly recommended to consult the engine manufacturer's service manual or a qualified technician for precise instructions:


  1. Visual Inspection: Start by visually inspecting the EGR cooler for any visible signs of damage, leaks, or excessive carbon buildup. Check for coolant leaks, cracks, corroded fittings, or any other visible issues.

  2. Pressure Testing: Perform a pressure test on the EGR cooler to check for leaks. Apply pressure to the coolant side of the cooler and monitor for any drops in pressure, indicating a leak.


  1. Scan Tool: Connect a compatible scan tool to the OBD-II port or manufacturer-specific diagnostic port to retrieve error codes and live data from the engine control module (ECM). Look for error codes related to EGR system malfunctions, such as insufficient flow or excessive temperature.

  2. Performance Testing: Monitor the engine's performance during operation. Look for signs of reduced power, increased smoke emissions, or poor engine performance that may indicate a problem with the EGR cooler.


  1. Disconnection: Before replacing the EGR cooler, disconnect the negative battery cable to prevent any electrical issues or accidental starting of the engine.

  2. Access and Removal: Locate the EGR cooler on the engine. It is typically connected to the intake manifold and the exhaust system. Remove any necessary components obstructing access to the cooler, such as air intake components or heat shields. Carefully disconnect the coolant lines, EGR valve, and any electrical connections attached to the cooler. Loosen and remove the mounting bolts or clamps securing the cooler.

  3. Cleaning: Thoroughly clean the mating surfaces of the intake manifold and exhaust system where the EGR cooler is installed. Remove any residue, old gasket material, or carbon deposits.

  4. Installation: Install the new EGR cooler following the manufacturer's specifications and procedures. Ensure proper alignment and tightness of coolant lines, fittings, and electrical connections. Replace any required seals, gaskets, or O-rings.

  5. Reassembly: Reassemble the engine components, ensuring proper alignment and connection of all wiring, hoses, sensors, and components removed during the disassembly process.

  6. Testing and Verification: Start the engine and carefully monitor for any coolant leaks, abnormal noises, or irregularities in engine performance. Perform additional checks, such as pressure tests, to verify the repair.

Please note that the exact steps and procedures can vary significantly depending on the specific engine model, manufacturer, and other factors. Always consult the appropriate service manual or seek assistance from qualified technicians for the specific engine and EGR cooler you are working on.

Previous article How to inspect, diagnose and replace a EGR valve
Next article Which is the best engine, Cummins, Paccar, Volvo/Mack, or Detroit Diesel?