Cause of error code E52

Return water temperature sensor is open. No continuity.

Solution for error code E52

1. Is harness plugged into Return Temperature Sensor? Is harness plugged into Control Module J5?
Yes: -> 2
No: Insert harness

2.Check continuity of brown wires between Return Temperature Sensor and Control Module J5-4 and J5-12 Continuity?  
Yes: -> 3
No: Replace Wires

3. Measure return temperature sensor resistance with digital meter. Estimate sensor temperature. Does temperature fall within ranges shown on chart? 
Yes: Replace control module
No: Replace retun temperature sensor