John Deere 2790.18 – Engine Control Unit (ECU): Turbocharger Compressor Outlet Temperature (Calculated) High / Above Normal Operational Range

The calculated turbocharger compressor outlet temperature is high or above normal operational range. There is no physical temperature sender/sensor for the turbocharger compressor outlet; it is a virtual value calculated by the control module using inputs from the Compressor Inlet Temperature sensor, the Manifold Air Temperature (MAT) sensor, and the Turbocharger Speed sensor. When this calculated value exceeds the safe threshold, the code is triggered, and the engine will typically enter a derate mode to protect the turbocharger and engine components from heat-related damage. The underlying condition is usually a restriction in the cooling or intake system, extreme ambient temperatures under heavy load, or a skewed input sensor feeding the ECU bad data.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 9570 STS
• 9660 STS
• 9670 STS
• 9760 STS
• 9770 STS
• 9870 STS
• 3520
• 3522
• 7030
• 8030
• 7R
• 8R

1. 1

   Check for other active codes related to the Manifold Air Temperature sensor (SPN 105), Turbocharger Speed sensor (SPN 103), or EGR Valve Position (SPN 2791)

2. 2

   Inspect the Charge Air Cooler (intercooler) and radiator exterior fins for blockages caused by dirt, dust, or crop debris

3. 3

   Inspect the primary and secondary engine air filters for severe restrictions

4. 4

   Evaluate operating conditions to determine if the machine was under maximum load in unusually high ambient temperatures

1. 1

   Address Sensor Faults First

   Connect John Deere Service ADVISOR. If there are active codes for the MAT sensor, Turbo Speed sensor, or Intake Pressure, diagnose and replace those physical sensors first.

2. 2

   Clean the Cooling Package

   Thoroughly blow out the radiator, Charge Air Cooler (intercooler), and oil cooler assemblies with compressed air. Ensure maximum airflow through the cooling package.

3. 3

   Service the Air Intake

   Remove and inspect the engine air filters. If they are dirty or restricted, replace both the primary and secondary filters. Do not attempt to blow out and reuse the inner safety filter.

4. 4

   Inspect Intake Piping

   Check the piping between the turbocharger, the Charge Air Cooler, and the intake manifold for internal blockages, heavy soot/oil buildup, or collapsed hoses.

5. 5

   Test Sensor Data (Live Data)

   If the cooling package is clean and filters are new, use Service ADVISOR to monitor the live data for the Turbocharger Speed and Manifold Air Temperature. If a sensor is reading skewed (e.g., reading 200°F when the engine is cold), replace the skewed sensor even if it hasn't triggered its own fault code.

6. 6

   Inspect the VGT / Turbocharger

   If all sensors are reading accurately and the cooling system is clear, the Variable Geometry Turbocharger (VGT) actuator may be sticking, or the turbocharger bearings may be failing, causing genuine excessive heat. Repair or replace the turbocharger assembly.

7. 7

   Clear and Test

   Clear the ECU codes and run the machine under a heavy load to verify the calculated temperature remains within specification.