Automotive Technician Training 101: Signs It’s Time to Replace the Engine Coolant Temperature Sensor

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The engine coolant temperature sensor (CTS) is a crucial component in most modern car engines. Its role is to continuously measure the temperature of the engine’s coolant, often by continuously reading the electrical resistance of the coolant. This will fluctuate depending on the engine’s heat, with the sensor reacting to the coolant’s status and feeding that information into the vehicle’s regulating computer, which will adjust engine performance accordingly. When this little sensor starts misfiring, engine issues can soon follow.

Pull on that auto mechanic detective cap: Here’s how to spot the telltale signs that this senor isn’t working well anymore.

The Check Engine Light Is Triggered and Stays Lit

A number of issues can set off the all-important check engine light. Depending on the type of vehicle, this can include an issue with the CTS. Given the crucial role that the sensor plays in the overall process of regulating the engine and its fuel consumption, any detected issues with this piece is certainly enough to justify this general alert in most models.

Of course, a check engine light could mean any number of things. That’s why a professional with automotive technician training will know to see if this sign coincides with other potential symptoms in order to come up with an accurate diagnosis.

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The engine warning light can be an ambiguous indicator, but it can mean an issue with the CTS

Fuel Is Being Guzzled at an Unusual Rate

The role of the CTS is to ensure that the vehicle has more information with which to efficiently run the engine. With the CTS either compromised or fully dead, the result can be a more poorly managed engine. An engine with a faulty CTS will often consume more fuel than normal, as the engine’s coolant temperature is improperly read. Given that this symptom will continuously pummel the owner’s pocket once it appears, it should promptly spur a sensor check, and replacement if a faulty CTS is confirmed.

Pros with Auto Mechanic Careers Know to Check the CTS When They See Black Smoke

We all know the scene: an aging clunker is started up, the engine struggles and with a bang, a cloud of black smoke escapes the rattling exhaust. However, pros with auto mechanic careers know that black smoke doesn’t just occur in older cars.

Black smoke from an otherwise healthy vehicle’s exhaust can be an indication that a faulty CTS is sending incorrect “cold” readings. This overly enriches the fuel mixture and causes excess gas to be burnt in the exhaust housing itself. Embarrassing, dirty, and polluting, there is rarely smoke without fire—or a frazzled sensor in this case.

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Usually associated with aging vehicles, black smoke can also signal a troubled CTS

Trouble Starting a Warmed-Up Engine Can Point to CTS Issues

Typically, most issues with vehicles not starting occur when the driver tries to start a cold engine after a period of inactivity. This can be caused by a range of garden-variety issues.

However, having a recently driven vehicle with a warmed-up engine fail to start is a less common problem. A broken sensor, in this situation, could be calibrating the wrong fuel mixture which in turn chokes the engine. Once the usual ‘failure to start’ issues—like a dead battery or broken starter—are ruled out, it’s time to investigate a potential CTS problem.

Building your knowledge as an automotive technician can be a rewarding career path.

Contact Automotive Training Centres to get enrolled in an automotive school in Vancouver today.

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