CCU 001638.16 – Hydraulic Oil Temperature Hot

CCU 001638.16 (CCU 1638.16)

Code: 001638.16

Shortcode: 1638.16


This fault code indicates that the hydraulic oil temperature sensor has detected oil temperatures higher than normal operating levels, but not yet reaching a critically hot threshold. This situation can still adversely affect system efficiency and increase wear on hydraulic components.


The function of the hydraulic system is degraded, limiting some operations to prevent damage due to elevated temperatures.


  • Check Hydraulic Oil Level: Verify that the hydraulic oil is at the proper level and top up if necessary. Low oil levels can lead to higher operating temperatures.
  • Inspect Transmission Components: If the issue arises predominantly during transport speeds, inspect the transmission suction screen for clogging and the transmission scavenge pump for any damage or wear.
  • Evaluate Cooling System: Ensure that the hydraulic system’s cooling components are functioning correctly and efficiently.
  • System Monitoring: Monitor the hydraulic system during operation to identify potential causes of increased temperature, such as excessive load or insufficient cooling.
  • Reset and Test: After performing necessary maintenance, reset the CCU and test the hydraulic system to ensure temperatures remain within normal ranges during operation.


Regular maintenance and monitoring of hydraulic oil levels and cooling systems are crucial to maintaining optimal temperatures and preventing overheating.

Control Units: John Deere

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