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Error Code P1285 is defined as Cylinder Head Over Temperature Condition, a condition that usually happens when the vehicle overheated.
This error code is a manufacturer-specific trouble code, meaning it does NOT apply to all vehicles equipped with OBD-II system or vehicles made since 1996 up to present. Rather, it applies to select manufacturers, particularly Ford vehicles.
Engine overheat condition is determined by the Cylinder Head Over Temperature sensor. An overheat condition means the temperature gauge reads temperature that is higher than normal or more than the allowable temperature for the engine to function properly.
As with other error codes, P1285 activates the Check engine light and registers the error code. For the overheat condition, the most common symptom is the emission of excessive white smoke from the tailpipe.
Overheat condition can be due to multitude of things, such as defective thermostat and coolant loss, which is usually caused by a leak. Other possible caused for this code includes:
- Engine overheat
- Faulty cylinder head temperature sensor
- Low engine coolant level
- Open or shorted cylinder head temperature sensor
- Poor electrical connection in the cylinder head temperature sensor
How to Check
When this code appears, the first thing you need to determine is whether the vehicle overheated, and how many miles are on it.
Then, you need to check the coolant level and condition.
Next, check for coolant leaks. Also, check whether the cooling fan is working properly in both high and low speeds. You can do this by starting the vehicle and disconnecting the ECT (engine coolant temperature) sensor and see whether the high-speed fan turns on within 5 to 10 seconds.
If you have a personal scanner, check whether it can access the data stream. If you can use the data stream, check the Cylinder Head Temperature (CHT) sensor resistance. It should be between 0.067 kilo ohms to 965 kilo ohms. The higher the temperature, the lower the reading there is for resistance. The CHT is located on the rear of the left side head.
How to Fix
As with other overheat conditions, the first thing you need to do once you realize you’re having an engine overheat is to turn off the engine and let it cool down before doing anything on it. Never take off the radiator cap. Then, refill or add antifreeze or coolant.
Next, check for leaks, bursts, and blockages in the hoses.
Monitor the temperature gauge carefully.
If you have determined the cause of the overheat is the faulty cylinder head temperature sensor, then have that sensor replaced.
Repair or replace open or shorted cylinder head temperature sensor.
Repair or replace electrical connection in the cylinder head temperature sensor.
Engine overheat condition can cause severe damage to your vehicle. Thus, it is important to get the problem addressed as soon as possible. Also, it always pays to keep a safety kit in your car.