Symptoms Of A Faulty Coolant Temperature Sensor

By Author: Many Autos
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One of the car engine management systems that monitors the temperature of the radiator coolant is the coolant temp sensor. The coolant temp sensor works properly by using an electrical circuit to monitor the coolant temperature. The sensor provides a signal to the vehicle’s computer, instructing it to make adjustments to the gas calculation and engine timing for maximum performance.
Because the vehicle engine requires less gas when warmed and more gas when cold, the car computer will adjust the engine performance setting if it receives a signal that the coolant temperature is above the normal operating temperature to prevent the engine from overheating and causing catastrophic damage.
A bad coolant temperature sensor may quickly damage your engine's performance because it plays such an important part in engine timing and calculation for optimal performance. As a result, you should constantly be on the lookout for signs of a faulty coolant temp sensor. Before your next MOT test, check MOT statusof your car and get it fixed by a competent car technician.
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... We'll go over how to detect if your coolant temp sensor is faulty, the indications and symptoms of a bad coolant temp sensor, and how to remedy the problem in this post.
Symptoms of a Malfunctioning Coolant Temperature Sensor
The coolant temperature sensor, like every other mechanical component in your car, produces symptoms to alert the driver when it fails. So, before a coolant temp sensor failure turns into a more serious transmission or engine repair, look for the following signs:
Irregular temperature readings - If your temperature gauge shows temperature swings or stays lower or higher than expected while the engine is operating, it might be a sign of a malfunctioning or faulty coolant temp sensor. You must call your mechanic to analyse and hunt down the problem with your cooling system, especially if the engine does not warm as it should. Find out the current MOT statusof your car to have your car mechanic repair this issue before your next MOT test. While the coolant temperature may be lower than the ambient air temperature, the coolant temperature might give the car computer incorrect data. Keep in mind that, in addition to a malfunctioning coolant temp sensor, there are a slew of other factors that might cause irregular or changing temperatures, including cylinder head leaks, low coolant levels, a failed radiator fan, and a broken pressure cap.
Black smoke from the exhaust tailpipe - Black smoke from the exhaust tailpipe is a frequent indicator of a faulty coolant temp sensor. A malfunctioning coolant temperature sensor will provide a cold signal to the automobile computer, fooling it and causing it to enrich the air/fuel mixture ratio excessively. The exhaust tailpipe will emit black smoke if the air-fuel combination gets too rich, preventing the gas from being properly burnt during the combustion process. In severe situations, the smoke may be so thick that driving the car with it is impossible. This will also fail the emissions test on your next MOT test. Look online for check my MOT history and see if there is a pattern of emission test failures in the past.
Engine overheating - While it is obvious that a failed or defective temp sensor would result in a cold reading, the coolant temp sensor might malfunction and produce a hot signal even while the engine is operating at normal operating temperatures in some instances. When this happens, your car's computer will believe the vehicle is running hot when it isn't. As a consequence, a dashboard warning light will illuminate, and your car will become slow. Have this issue repaired at your earliest convenience before total engine failure and before your next MOT testing service appointment to avoid a MOT test failure.
Poor fuel economy - Poor fuel efficiency is one of the most typical symptoms of a faulty coolant temp sensor. A faulty coolant temperature sensor will give the automobile computer a misleading value, disrupting correct gas and timing calculations. A malfunctioning temperature sensor will frequently provide a chilly signal to the computer, causing the computer to believe the car is constantly cold, even while it is running hot. As a result, fuel economy and engine performance suffers.
Rough Idle - Can a faulty coolant temperature sensor result in a rough idle? Yes, the air-fuel mixture will be adjusted as a result of the erroneous signal given to the car computer. The provided mixture will be insufficient, causing vibrations and shaking at idle or low speeds, as well as other odd behaviour and engine power loss.
Engine management light illuminates - A check engine light that illuminates indicates a potential problem with internal engine components or a malfunctioning electrical system. The engine warning light can be triggered by a number of things. You'll need a scan tool to analyse the automobile fast when the light is on. The fault codes will be read and translated in alphanumeric sequence by the diagnostic tool. Complete a MOT history checker for your car online and see if this light also appeared in past MOT tests. Each one symbolises a distinct issue. The following trouble codes are related to coolant temperature:

P0115: Indicates an intermittent problem with the coolant temperature circuit.
P0116: This code indicates an issue with the coolant temperature circuit range.
P0117: A low input in the coolant temperature circuit.
P0118: A high input in the coolant temperature circuit.
P0128: Shows that the coolant temperature is lower than the thermostat's typical operating temperature.
How to Repair Coolant Temperature Sensor Issues
You may believe that replacing the sensor is the best answer to this situation. In some cases, though, the sensor does not need to be replaced. As a result, knowing how to test coolant temperature sensors with a diagnostic machine, an oscilloscope or a digital multi-meter is critical. For example, a low coolant level will cause the coolant temp sensor to provide misleading readings. If this is the case, you may resolve the issue by filling up your coolant to the proper level.
Working under the bonnet may be dirty, especially if you're cleaning a region that hasn't been cleaned in a long time. So, you'll need a mechanic glove, goggles, and a long-sleeved shirt. Organising and maintaining your mechanic tools near at hand can help you do the job faster. Replacing a temperature sensor is a simple job that anybody familiar with the ‘under the bonnet' components can complete:
Locate the temperature sensor - The temperature sensor is usually found near the radiator or in the thermostat box. The temp sensor may be situated in the rear of the engine in some cars, necessitating the use of a touch light to detect it. The upper radiator hose is linked to the thermostat housing; trace the upper hose to the thermostat housing and look for the CTS there.
Remove the electrical connectors - An electrical connector connects the temp sensor to the car computer. The connector must be carefully unplugged since it is fragile and can break. Always check for rust on electrical connectors and clean them if you discover any.
Unscrew the sensor with a long socket and ratchet handle - Coolant temperature sensors are generally mounted like a spark plug, so you'll need a long socket and ratchet handle to remove them. If the sensor refuses to break free, don't put too much pressure on it. A spritz of break-free solvent will make it much easier to slack. Before removing the sensor, remember to remove the radiator cover. Unscrew the CTS by hand after it has become loose. Because the antifreeze will leak from this location, make sure you refill it.
Replace with new sensor - Place both sensors next to each other and compare them before installing the new one. If you buy an aftermarket item, this is typically required. Clean the debris from the old sensor from the CTS housing using a cloth. Place the new CTS in the housing and hand-thread it. Tighten it with a torque wrench to the manufacturer's stated range once you've included the sensor and ensured it didn't miss any threads.
Reinstall the electrical connectors - After tightening the sensor, the electrical connector must be reinstalled. Check for rust on the electrical connections before reconnecting it to the CTS. Replace any fasteners on the sensor and check for proper fit. Replace the pressure cap on the radiator and refill the coolant. Start the engine and check to see whether the temperature indicator is accurate.
Test the car: Take the car for a spin to discover if your hard work has finally paid off. Recheck the coolant level once you've returned from the test drive to see whether it's decreased, and if it has, refill it. Give yourself a pat on the back if everything went smoothly.
Final Thoughts
Your vehicle's engine must maintain a certain temperature. If this is disrupted, it will overheat and most likely cause catastrophic engine damage. Car makers construct vehicles with antifreeze that flows through the radiator to keep the engine cold and prevent it from overheating. To guarantee that the vehicle engine operates at an average operating temperature at all times, the coolant must be monitored. As a result, a coolant temperature sensor is required (CTS).
Failure of the coolant temp sensor can cause particular engine problems, such as a burst head gasket or, in extreme cases, damage to the aluminium engine block. As a result, you should constantly be on the lookout for signs of a malfunctioning coolant temp sensor and either fix it yourself or contact your mechanic for a replacement.
Frequently Asked Questions (FAQ’s)
What is the purpose of a coolant temperature sensor?
The coolant temperature sensor monitors and measures the temperature of the engine coolant in the cooling system and informs the ECU how much heat the radiator released. The coolant temp sensor works in tandem with the ECU, continuously detecting and monitoring coolant temperature to guarantee that the vehicle engine operates at an optimal operating temperature.
What is the lifespan of a coolant temperature sensor?
Coolant temperature sensors that are defective are frequent. It is possible to corrode the CTS endpoint that comes into contact with the coolant if you do not do the normal and planned maintenance recommended by your manufacturer. Sensors for coolant temperature can last up to 100,000 miles. The sensor, on the other hand, might fail prematurely if your engine cooling system is not properly maintained.
Is the fan controlled by the temperature sensor?
The coolant temperature is monitored and measured by the temp sensor. The sensor then communicates the temperature data to the ECU, which may or may not trigger the radiator fan to turn on or off depending on the measurement.