Pinpoint Test B: The Engine Overheats

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Normal Operation and Fault Conditions

The engine cooling system maintains the engine temperature during operation. Correct coolant flow through the engine, radiator and remainder of cooling system passages and components is essential to maintaining a correct engine temperature.

Engine coolant flows primarily from the engine to the radiator circuit and back to the coolant pump. Coolant is sent from the coolant pump through the engine block and cylinder head. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump circulates the coolant. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat is opened, coolant flows through the radiator circuit to transfer engine-generated heat to the outside air.

Engine overheating generally occurs when there is a disruption in the ability to control either coolant flow at the correct rate, the inability to transfer heat from the engine through the coolant (including low coolant) or an inability to transfer engine-generated heat to the outside air through the radiator.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM P0217:00	Engine Coolant Overtemperature Condition: No Sub Type Information	Sets in the PCM when an engine overheat condition was sensed by the CHT sensor.
PCM P1299:00	Cylinder Head Overtemperature Protection Active: No Sub Type Information	Sets in the PCM when an engine overheat condition was sensed by the CHT sensor.

Possible Sources

Low coolant level
External engine coolant leak
Airlock in system
Pressure relief cap installation
Restricted airflow through A/C condenser/radiator
Internal engine coolant leak
Coolant condition/concentration
Accessory drive components
Non-OEM engine enhancement components
Cooling fan
Cooling fan clutch
CHT sensor
ECT sensor
Radiator
Thermostat
Coolant pump
Coolant flow restriction
Engine oil in engine coolant
Transmisison fluid in engine coolant
Active grill shutter assembly

B1 CHECK COMPONENTS FOR DAMAGE OR FAILURE
- Visually inspect the possible sources for obvious signs of physical damage or failure.
Are any concerns present?

Yes REPAIR as needed.

No GO to B2

B2 CHECK FOR NON-OEM ENGINE ENHANCEMENT COMPONENTS
- Check the engine for any non-OEM components.
Are there any non-OEM components on the engine?

Yes ADVISE the customer the engine modifications may be causing the engine to overheat.

No GO to B3

B3 CHECK FOR AN AIRFLOW OBSTRUCTION AND MISSING AIR DEFLECTORS

NOTE: Verify no vehicle front end damage is present.
- Check the radiator or A/C condenser for an external obstruction such as leaves or cardboard and verify all air deflectors are present.
Is an airflow obstruction present or air deflectors missing?

Yes REPAIR as necessary.

No GO to B4

B4 CHECK THE ENGINE COOLANT LEVEL AND PRESSURE TEST THE COOLING SYSTEM
- Ignition OFF.
- Visually check the engine coolant level in the coolant expansion tank and adjust as necessary. Pressure test the cooling system.
Does the engine cooling system leak externally?

Yes REPAIR or INSTALL new components.

No GO to B5

B5 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK

Inspect the engine coolant in the degas bottle for signs of engine oil or transmission fluid.

Is engine oil or transmission fluid evident in the coolant?

Yes

If engine oil is evident, REFER to: Engine - Diesel . If transmission fluid is evident, INSTALL a new transmission fluid cooler. REFER to: Transmission Fluid Cooler - Backflushing and Cleaning - Vehicles With: Transmission Fluid Heat Exchanger . REPAIR the transmission as necessary. REFER to: Diagnosis By Symptom .

GO to B6

B6 CHECK THE FUEL AND TRANSMISSION FLUID FOR COOLANT

Drain the fuel from the fuel conditioning module. Remove the oil level indicator from transmission.

Is coolant evident in the fuel or transmission fluid?

Yes	INSTALL a new transmission fluid cooler. REFER to: Transmission Fluid Cooler - Backflushing and Cleaning - Vehicles With: Transmission Fluid Heat Exchanger . REPAIR the transmission as necessary. REFER to: Diagnosis By Symptom .

GO to B7

B7 CHECK THE ENGINE OIL FOR COOLANT
- Remove the oil level indicator from the engine.
Is coolant evident in the engine oil?

Yes REFER to: Engine - Diesel .

No GO to B8

B8 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES

NOTE: Use UView® Combustion Leak Tester part number UVU560000-R or equivalent.
- Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.
Are combustion gases present?

Yes REFER to: Engine - Diesel .

No GO to B9

B9 CHECK THE COOLING FAN CLUTCH OPERATION
- Ignition OFF.
- Check the cooling fan clutch operation. REFER to: Cooling Fan Control .
Is the cooling fan clutch operation OK?

Yes GO to B10

No INSTALL a new cooling fan clutch. REFER to: Cooling Fan .

B10 CHECK THE COOLANT PUMP OPERATION
- Start the engine.
- Allow the engine to run for 10 minutes. Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.
Is the heater outlet hose hot?

Yes GO to B11

No INSTALL a new coolant pump. REFER to: Coolant Pump .

B11 CHECK THE THERMOSTAT OPERATION
- Start the engine.
- Allow the engine to run for 10 minutes. Place the climate control function selector in the MAX HEAT position. Feel the upper radiator hose.
Is the upper radiator hose hot?

Yes CHECK the temperature gauge operation. REFER to: Instrumentation, Message Center and Warning Chimes .

No GO to B12

B12 VISUALLY INSPECT THE THERMOSTAT

Carry out the Thermostat Visual Inspection .

Is the thermostat damaged?

Yes	INSTALL a new thermostat. REFER to: Thermostat .

No	INSTALL a new thermostat. REFER to: Thermostat . If the engine still overheats, INSTALL a new radiator. REFER to: Radiator .