Symptom
When the coolant temperature is above 107 °C (224°F), DTC 325 will be set and the control system will command less fueling. A power loss may also occur.
When the coolant temperature is above 109 °C (228 °F), the red ENGINE lamp will be illuminated and DTC
321 will be set.
When the coolant temperature is above 112 °C (234 °F), the red ENGINE lamp will flash, an audible alarm
will sound, and DTC 322 will be set. If the vehicle has the warning protection feature enabled, the engine will
shutdown after 30 seconds.
Cause
• Low engine coolant level
• External coolant leaks
• Internal or external radiator blockage
• Broken/worn accessory drive belt
• Accessory belt tensioner failure
• Coolant thermostat stuck (closed)
• Slipping cooling fan drive clutch
• Water pump failure
• Cooling fan blade assembly wrong/damaged
• Inoperative electric cooling fan
• Instrument panel gauge error
• Engine Coolant Temperature (ECT) sensor biased
• Incorrect radiator
• Missing coolant thermostat
• Internal coolant leak
• Chassis effects, transmission, after-market equipment
Tools
• Radiator pressure test kit and adapter
• Regulated compressed air
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM) with thermocouple
