P00B6 - Radiator Coolant Temperature Sensor / Engine Coolant Temperature Sensor Correlation
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P00B6 is stored when the Engine Control Module (ECM) detects a correlation error between the Engine Coolant Temperature (ECT) sensor 1 and the Radiator Coolant Temperature (ECT) sensor 2. The ECM monitors these two sensors to verify thermostat operation and cooling efficiency. If the temperature delta between the two sensors is outside of a calibrated window during engine warm-up or steady-state operation, the fault is triggered. This can affect closed-loop fuel control and cooling fan strategy.
Possible Causes
Faulty Radiator Coolant Temperature (ECT 2) sensor
Faulty thermostat (stuck open or opening prematurely)
Corrosion in connectors or wiring harness (causing resistance issues)
Low coolant level or air pockets in the cooling system
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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