Caterpillar Fault Code
Free · no signupE001 (Level 2)
Power Derate (Limiting RPM).
System
Cooling
Symptom
Power Derate (Limiting RPM).
Diagnosis & fix steps
LOGIC: Coolant temp has hit the "Action" threshold (approx. 107°C / 225°F).
ACTION: The ECM will cut fuel to protect the head. Check coolant level and fan belt tension.
Red Seal field insights
Specs: ECM will reduce power by 25%.
RED SEAL FIX: Check the Thermostat (Regulator). CAT regulators have a rubber seal that can "roll," preventing the valve from opening fully.
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