QA

Quick Answer: Cooling Fans Only Work When Temp Sensor Is Unplugged

What happens if I unplug coolant temperature sensor?

What Happens If You Unplug The Coolant Temp Sensor? Unplugging the engine coolant sensor while the car is running will likely cause the engine to stumble and run rough. The engine light may not come on imminently, but a DTC (Diagnostic Trouble Code) will be logged in the PCM.

Will the cooling fan when I disconnect temperature sensor?

you will set a trouble code, check engine light on, radiator cooling fan should come on. Don’t drive car with the sensor disconnected. Your temperature gauge would stop working and this would in turn switch off the engine via the ECM.

What are the symptoms of a faulty temperature sensor?

What Signs May Signal Your Coolant Temperature Sensor May Be Failing? Poor Fuel Economy. Irregular Temperature Readings. Black Smoke from Your Exhaust. Your Engine is Overheating. Your Check Engine Light is On.

What happens when a temperature sensor fails?

If the coolant temperature sensor malfunctions, it can transmit a false signal to the computer. And the response of the computer may unbalance the timing and fuel calculations. It is also common for a coolant temperature sensor to fail without warning and send permanently cold signals to the computer.

Does temperature sensor turn on fan?

On most modern cars, the cooling fan is controlled by the Engine Control Unit (ECU) which gets a signal from the coolant temperature sensor. If it’s not working, the fan won’t turn on when it needs to, which means the engine might overheat.

What causes cooling fans not to come on?

Six things may prevent an electric cooling fan from coming on: Engine thermostat is stuck OPEN (engine never gets hot enough to turn on the fan) Faulty fan relay. A wiring problem (blown fuse, loose or corroded connector, shorts, opens, etc.).

Can you bypass a temperature sensor?

You can bypass it with a regular resistor, but you have to know the value associated with the thermister. To find the value: -Disconnect the thermister, and apply a meter to it and read initial resistance value.

What are the symptoms of a faulty cooling fan switch?

Common signs include engine overheating, the Check Engine Light coming on, and a broken or shorter signal wire.

Can a coolant temperature sensor cause rough idle?

A faulty coolant sensor that always reads cold may cause the fuel control system to run rich, pollute and waste fuel. A coolant sensor that always reads hot may cause cold driveability problems such as stalling, hesitation and rough idle. This also affects engine performance and fuel economy.

Will engine coolant temperature sensor keep car from starting?

The sensor will not cause a no start. It could cause a hard start and a rich or lean condition only.

Can low coolant cause fan to not work?

What causes the radiator to stop working? The most common reasons a radiator fan is not working are luckily due to a blown fuse, bad relay, or a broken wire. It can also be caused by a faulty coolant temp sensor, low coolant level or the fan itself can be damaged.

Can a temp sensor affect engine starting?

If the sensor is reading too high of temperature when compared to the ambient air temperature sensor when first started then the computer would see it as a problem and turn on the check engine light to use a known good reading. No start will not be caused by the sensor.

How do you test a temperature sensor?

Gently lower the end of the sensor into the water until the entire device is fully submerged. Wait a minute or so for the screen to give you a reading of the cold water. Once you have a reading, write down the measurement for reference. A common reading for a temperature sensor in cold water is around 5 volts.

How many ohms should a coolant temperature sensor have?

In cold engine and an ambient temperature of 20 ºC the sensor resistance is between 2000Ω and 3000Ω. After the engine start, coolant temperature begins to rise. ECT gradually heats and its resistance reduces proportionately. At 90 ºC its resistance is in the range of 200Ω to 300Ω.

Why would the temperature gauge stop working?

The most common reason your temperature gauge staying on cold is a faulty coolant temperature sensor. It can also be caused by bad wirings between the cluster or the sensor. In some cases, it can also be a stuck thermostat causing the engine not to heat up properly.

Can a bad temp sensor cause stalling?

The signal from the coolant temperature sensor tells the engine’s computer when to apply extra gasoline during a cold start. A faulty sensor can confuse the computer, keeping it from providing enough fuel. As a result, the engine may hesitate or stall.

Does the thermostat control the radiator fan?

The thermostat opens and closes when there is a need to. How it works is simple. When the temperatures outside are cold the thermostat stays closed and the coolant stays in the engine. When the coolant reaches the working temperature the thermostat opens and the coolant circulates through the cooling system.

What tells the cooling fan to come on?

The engine temperature should trigger the fan to turn on. It will also turn the fan off once the engine has cooled to under 200 degrees. You may have heard of a part called the radiator fan switch or temperature fan switch. This is linked to a thermostat and works much like your home’s HVAC system.