Symptoms of a Bad or Failing Coolant Temperature Switch (Sensor)

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Cost of Replacing a Bad or Failing Coolant Temperature Switch (Sensor)

Common signs include poor fuel economy, black smoke coming from the engine, engine overheating, and the Check Engine Light turning on. Our certified technicians can come to you and diagnose the problem. You will receive a $30 credit towards any follow-up repairs that result from the diagnostic. Following are example prices for Coolant Temperature Switch (Sensor) Replacement. Click on the button below to get an upfront quote for your car.

Cars Estimate Parts Cost Labor Cost Savings Average Dealer Price
2009 Nissan Frontier $119 $48.98 $70.00 23% $156.48
2009 Chevrolet Impala $87 $17.05 $70.00 30% $124.55
2005 Chevrolet Silverado 2500 HD $87 $17.05 $70.00 30% $124.55
2009 Lincoln MKZ $89 $19.20 $70.00 29% $126.70
2009 Mercedes-Benz G550 $107 $8.80 $98.00 32% $159.30
2014 Jaguar XFR-S $77 $6.68 $70.00 32% $114.18
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How to Diagnose a Bad or Failing Coolant Temperature Switch (Sensor)?

Coolant Temperature switch

The coolant temperature sensor, also known as the coolant temperature switch, is an engine management system sensor that is used to monitor the temperature of the engine’s coolant. Most coolant temperature sensors operate using electrical resistance to measure the temperature of the coolant. This signal is then sent to the computer so that changes can be made to the engine’s timing and fuel calculations for optimal performance, as engines require more fuel when they are cold, and less fuel when they are fully warmed up. The computer will also scale back engine performance settings if it detects that the engine temperature is too high, in order to protect the engine from possible damage due to overheating.

Because temperature plays such a vital role in engine performance calculations, any problem with the coolant temperature sensor can quickly translate into an engine performance issues. Usually a problem with the coolant temperature sensor will cause a few symptoms that alert the driver of a potential problem that should be thoroughly inspected.

1. Poor fuel economy

One of the first symptoms associated with a problem with the coolant temperature sensor is poor fuel economy. If the coolant temperature sensor goes bad it can send a false signal to the computer and throw off the fuel and timing calculations. It is not uncommon for the coolant temperature sensor to fail and send a permanently cold signal to the computer. This will cause the computer to think the engine is cold, even when it is not, and as a result will use more fuel than necessary. This will reduce fuel economy, and may hinder engine performance.

2. Black smoke from engine

Another symptom of a possible problem with the coolant temperature sensor is black smoke from the vehicle’s exhaust. If the coolant temperature sensor fails and sends a cold signal to the computer, this can confuse the computer and cause it to unnecessarily enrich the fuel mixture. If the fuel mixture becomes excessively rich to the point where the fuel cannot be adequately burned in the combustion chamber, it will burn up in the exhaust pipes and cause black smoke. In severe cases, the black smoke may be considerable enough to warrant not driving the vehicle.

3. Overheating engine

Another symptom of a problem with the coolant temperature sensor is an overheating engine. The coolant temperature sensor can also fail in a manner that causes it to send a permanently hot signal. This can cause the computer to incorrectly compensate for a lean signal, which can result in overheating, and even misfires or engine ping.

4. Check Engine Light comes on

An illuminated Check Engine Light is another symptom of a potential problem with the coolant temperature sensor. For some vehicles the computer will set off a Check Engine Light if it detects a problem with the sensor’s signal or circuit. The Check Engine Light will remain on until the issue is addressed.

The coolant temperature sensor is one of the most important engine management sensors, as its reading plays a key role in calculations which affect engine performance. For this reason, if you suspect that your coolant temperature sensor is having an issue, have the vehicle inspected by a professional technician from YourMechanic. They will be able to diagnose your vehicle and determine if you need a coolant temperature switch replacement.

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Peter

40 years of experience
1059 reviews
Peter
40 years of experience
Peter was outstanding .
1981 CADILLAC DEVILLE - COOLANT TEMPERATURE SWITCH (SENSOR) - SUN CITY, ARIZONA

David

7 years of experience
72 reviews
David
7 years of experience
Good guy.
2014 CHEVROLET TRAVERSE - COOLANT TEMPERATURE SWITCH (SENSOR) - HAINESPORT, NEW JERSEY

Dan

36 years of experience
611 reviews
Dan
36 years of experience
Excellent knowledgeable friendly Mech.
2004 FORD RANGER - COOLANT TEMPERATURE SWITCH (SENSOR) - JEFFERSON, GEORGIA

Nick

11 years of experience
90 reviews
Nick
11 years of experience
Nick is honest and knowledgeable, which is all that truly matters in a mechanic...but on top of that, he is a really nice guy. He knows his stuff and genuinely wants to help. We would recommend him to anybody!
2004 HONDA CIVIC - COOLANT TEMPERATURE SWITCH (SENSOR) - ELK GROVE, CALIFORNIA

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