2012 Ford Mustang 3.7L convertible


P1299 Cylinder Head Overtemperature Protection Active is the code I get and after changing the fan with resistor and the thermostat and checking all fuses and relays my cooling fan doesn’t engage and with the a/c on max cool the clutch isn’t engaging because the fan isn’t coming on with the a/c like it usually does, I don’t know what else to try and when we jumpered the relays we tried the high with a wire and the fan kicked in and the a/c clutch engaged but when we jumpered the low relay the fan didn’t come on or the a/c clutch didn’t engage, What else is there to do?

According to the Chilton Manual and the Mitchell Manual if Code P1299 Cylinder Head Overtemperature Protection Active is active you will need to perform the following Pinpoint Test. No information was found on the code in the Motor Manual.

Pinpoint Test : The Engine Overheats

Normal Operation

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 heads. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump, operated by engine rotation through a pulley driven by the accessory drive belt, 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 P1299 Cylinder Head Overtemperature Protection Active
  • Low coolant level
  • External engine coolant leak
  • Air lock in system
  • Pressure relief cap installation
  • Restricted airflow through the A/C condenser/radiator
  • Internal engine coolant leak
  • Coolant condition/concentration
  • Accessory drive components
  • Non-OEM engine enhancement components
  • Electric cooling fan
  • Engine Coolant Temperature (ECT) gauge
  • ECT sensor (5.4L engine)
  • Cylinder Head Temperature (CHT) sensor
  • Heater core
  • Coolant pump
  • Radiator
  • Thermostat
  • Coolant flow restriction
Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.