As car enthusiasts, we love the sound that a gasoline engine creates and the adventures we take on. All the systems in your engine work together to create reliable and fuel-efficient power. The over-temperature protection system is one of those.

It protects your engine from overheating by turning it off when it reaches a certain temperature. Of course, overheating is a serious engine condition and rarely happens. The P1299 check engine light code is for when it occurs.

This guide will delve into all the symptoms and causes of the P1299 code. It will also show you how to diagnose the trouble code and even potential fixes for the root cause.

What is the P1299 Code, and What Does It Mean?

The complete error message for the P1299 code “Cylinder head Over-temperature Protection Active.” Now, Ford, Land Rover, Lincoln, Mazda, and Mercury use this code for an overheating cylinder head. The trouble code may be for a different issue if your car is not from one of these manufacturers.

Essentially, your cylinder head is the top cover the cylinders push against to create combustion. This creates a lot of heat which the radiator and coolant dissipate. If your cylinder head reaches a certain temperature outside of the normal range, you will have a P1299 code.

Where Is the Cylinder Head Temperature Sensor Located?

The cylinder head temperature (CHT) sensor is in the cylinder head. Your cylinder head is bolted to the crankcase and the CHT sensor takes the place of one of those bolts, performing two functions. It should be next to the cylinder head between the spark plug hex.

What Causes the P1299 Code?

Your coolant system is the primary heat dissipation system in your vehicle. If it fails, your engine will overheat. That being said, it’s not the only cause of the P1299 code. Here are the most common causes:

• Coolant issues
• Faulty thermostat
• Malfunctioning CHT sensor
• Failed wiring harness.

Coolant Issues

A radiator uses a system of pipes and a water pump to push coolant and remove heat from the engine. One of the principal causes of the P1299 code is this system not having enough coolant to dissipate heat anymore. 

Any failure of the coolant system itself can also cause this trouble code. A faulty water pump, a leaking radiator, or a hose leak can cause the system to malfunction.

Faulty Thermostat

Your thermostat controls the amount of coolant circulating through the coolant, depending on engine temperature. When the thermostat fails, it gets stuck in an open or closed position. If it is stuck closed, it can no longer adjust the flow of coolant, no coolant may flow through the system and the engine will overheat, causing the P1299 code. Check our catalog for a quality replacement thermostat. 

Malfunctioning CHT Sensor

The CHT sensor’s main purpose is to prevent the cylinder head from reaching a temperature that can cause warping or irreparable damage. It does this by turning off the engine when it reaches a certain temperature.

Of course, a malfunctioning sensor will activate this protection mechanism before this temperature is reached, which causes the ECU to log this trouble code.

Failed Wiring Harness.

Connecting your ECU, battery, and sensors is the wiring harness. It carries voltage to and from the ECU to the CHT sensor. Damage to the wiring harness means it can no longer perform this function and the sensor itself cannot function. As a result, the P1299 code will be logged.

What Are the Common Symptoms of P1299 Fault Code?

The source of this code is the activation of the overtemperature protection. Hence, there aren’t many symptoms before it activates. Here are a few common ones:

Check Engine Light

The check engine light illuminates whenever a drivetrain code is logged. This includes your engine, transmission, and emissions system. This light can illuminate even if the engine is not overheating as maybe the CHT sensor is malfunctioning.

Limp Mode

Limp mode is almost a given with this issue. This is because driving with an engine that is overheating will damage its internal components. Limp mode prevents you from accelerating above a certain speed or limits you to low gear. With a P1299 code, your engine may turn off to prevent further damage.

Reduced Fuel Economy

Car engines operate at a certain optimal temperature. Fuel flow characteristics mean that if your engine is consistently operating at high temperatures, it may consume more fuel than normal.

Will a Cylinder Head Temp Sensor Cause a Car Not to Start?

A CHT sensor can directly cause your vehicle to not start. This would not be because your engine is overheating on start, but because the voltage output of the sensor indicates that it is overheating. Of course, the sensor or related components are malfunctioning.

How to Diagnose and Fix the Cause of P1299 Code

Engine diagnostics can seem daunting and complicated to even the most experienced car owners. For this trouble code, there are only a few tools and techniques that you need.

OBD-II Reader

An OBD-II reader is an essential diagnostic tool. It allows you to interface with your ECU and reads the trouble codes that have been logged. This system allows mechanics to diagnose vehicle issues without expensive tools or complicated dismantling.

To scan for trouble codes, plug the scan tool into the connection port that is often located on the passenger side dash.

Inspect the Vehicle

Here, you need to check your engine for external signs of damage. First, check your water pump and coolant system. Look for signs of corrosion on the water pump and cracked coolant hoses.

Any coolant leaking from the radiator means it needs to be replaced. Coolant smells sweet and is green or pink in color. While you’re there, check that your radiator fan spins smoothly. You can do this by turning the vehicle on and listening for any excessive whining.

Your water pump belt can also cause issues. As these components need to be replaced together, check that your water pump is intact and not damaged.

Check your CHT sensor and wiring harness for damage. Any fraying or loose bits on the wiring harness are a cause for concern. Your CHT sensor should have no corrosion and melted plastic. The brass plug should not be warped in any way.

Wiring Harness Test

For this test, you will need a multimeter to measure the voltage coming through the wiring harness. Check your owner’s manual for the correct sensor configuration. Most sensors are two pins, with one providing power and another signal.

First, contact your red probe to the power terminal and the black probe to the vehicle chassis. The black probe provides grounding and the red will measure voltage from the sensor. You should get around 0.5V on the signal pin and 13V on the power terminal.

How to Fix a P1299 Code

Your engine may have already been damaged because of overheating. Before you continue, you need to check that your spark plugs are intact. A damaged electrode can break off and wreak havoc on your engine internals.

Replace your oil, coolant, and belts as it is likely that these have either dried up or will fail soon. You should replace your oil filter and transmission fluid, as overheating degrades both these components.

Does P1299 Clear Itself?

The seriousness of this code means you should not allow the engine to run for long periods. These systems are designed to prevent over-temperature, but even reaching the protection can damage components. Clear the codes with an OBD-II reader and ensure that the coolant system is running before resuming.

Is It OK to Drive with P1299?

Even if you can start your vehicle, you should avoid driving it. Damage to the cylinder head, head gasket, and piston rods are all expensive fixes that can occur if your engine overheats.

Fix the P1299 Code Using Quality Parts!

Diagnosing and clearing a P1299 code can be troublesome. You may need to replace multiple components and can’t afford to deal with parts that don’t fit or unreliable components.

Here at, eEuroparts.com, we stock all the genuine, aftermarket, and OEM parts that you might need. All you need to do is pick your vehicle from the dropdown menu and purchase your parts. All our components are tailored for your vehicle and are picked for their reliability.