John Deere 2659.02 – ECU: EGR Flow/Temperature Mismatch

The Engine Control Unit (ECU) senses a mismatch between the two calculation methods used to determine the EGR flow. Specifically, the EGR flow measured by the delta pressure sensor is significantly higher than the EGR flow measured by the temperature differential. When this discrepancy occurs, the EGR flow correction factor reaches its minimum limit, triggering the code. This typically causes the ECU to derate the engine and force the EGR system to run in an Open-Loop state.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7630
• 7730
• 7830
• 7930
• 8235R
• 8R Series
• 9230
• 9330
• 9430
• 9530
• 9630
• 9660 STS
• 9760 STS
• 4930
• 3520

1. 1

   Power Cycle Reset: Restart the engine to verify if the active Diagnostic Trouble Code reappears. Sometimes, the code can be corrected by resetting the communication messages during a restart.

2. 2

   Soot Accumulation Check: Inspect the EGR cooler and EGR valve for heavy soot deposits or clogging, which is the most likely cause of this mismatch.

3. 3

   Mechanical Inspection: Check if the EGR valve shaft is broken or if the butterfly valve is stuck.

4. 4

   Sensor Verification: If the physical EGR passages are clear, the fault is likely being caused by false readings from either the EGR Delta Pressure Sensor or the EGR Temperature Sensor.

1. 1

   Remove the EGR Valve

   Disconnect the electrical plug and remove the 3 mounting bolts securing the EGR valve.

2. 2

   Access the Cooler

   Remove the band-clamp on the cooler side to allow for easy inspection of the EGR cooler.

3. 3

   Clean the Components

   Use a flat blade screwdriver or a similar tool to carefully scrape and remove unwanted soot deposits from the valve and the entrance of the cooler.

4. 4

   Verify Valve Movement

   Once the deposits have been cleared, manually confirm that the butterfly valve moves freely. If the valve shaft is broken or the motor is burnt out, the EGR valve must be replaced.

5. 5

   Replace Sensors (If Necessary)

   If the valve and cooler are clean and functioning but the code persists, replace the EGR Delta Pressure Sensor or the EGR Temperature Sensor.

6. 6

   Reassembly

   Reinstall the valve and cooler connections. Note: OEM guidelines state that the metal EGR gaskets can often be reused if they are not damaged.

7. 7

   Clear Codes

   Cycle the power (using the operator key or toggle switch). The EGR faults will self-clear at the next power cycle if the valve motor is able to operate properly and the flow mismatch is resolved.