Cylinder head temperature (CHT) sensor codes

How its codes differ

• P1285 is the first over-temperature warning: on Ford's fail-safe cooling strategy it sets as the gauge goes into the red and the warning lamp comes on.
• P1299 means the protection has gone further: the engine computer is cutting cylinders and limiting engine speed, and will shut the engine off if the temperature keeps rising. Treat it as a stop-driving code.
• Both codes usually mean the engine really is too hot (low coolant, a coolant leak or coolant getting into a cylinder). A faulty sensor or software is the less common cause and is documented mainly for specific models, such as the 2024–2025 F-150 2.7L and the Mazda Tribute.
• P0217 (coolant over-temperature) comes from the coolant temperature sensor and often appears with P1285 or P1299 when the engine is genuinely overheating.

Codes

• P1285

  Cylinder head temperature above the engine computer’s limit (Ford, Lincoln, Ford-built Mazda)

  Severity: Stop

• P1299

  Ford and Lincoln: cylinder head over-temperature protection is active (the engine computer's fail-safe cooling mode)

  Severity: Stop

Signs it's failing

• Check engine light with P1285 or P1299, often with an over-temperature message
• Temperature gauge in the red
• Loss of power, rough running or engine speed limited (fail-safe mode)
• Engine shutting off after the warning lamp flashes
• Cooling fan running at the wrong times when the sensor reads wrongly (Mazda Tribute)

How to test it

1. Stop the engine and let it cool completely, then check the coolant level in the reservoir and look for wet spots, crusty residue or white exhaust smoke. (Use caution)

   Warning: Never open the radiator or reservoir cap while the engine is hot: steam and hot coolant can scald. Wait until the engine is cold.

2. Read all stored codes with a scan tool and note whether P0217, misfire or EGR codes are stored with P1285 or P1299. (Low risk)

3. Ask a dealer whether a bulletin, software update or updated sensor applies to your VIN. (Low risk)

4. Comparing the CHT reading with actual engine temperature, pressure-testing the cooling system and replacing the sensor are jobs for a shop. (Best left to a shop)

   Warning: These checks involve a hot, pressurised cooling system and a running engine. Leave them to a shop.

After the repair

• Confirm the coolant is full and stays full after several drives, with no leaks or white smoke.
• Clear the codes with a scan tool after the repair; on Ford's strategy the warning lamp does not go out on its own.
• Watch the temperature gauge on the next few drives, including under load.