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Discussion Starter · #1 ·
Hey my check engine light came on and it flashes four times. Does that necessarily mean its the coolant temp. sensor or could it be something in that area like the thermostat or could it just be a poor connection. Also, is it worth replacing it? Does the sensor just adjust the guage on the dash or does it actually help the ecu adjust the fuel consumption and all that stuff. Let me know. thanks.
 

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There are two separate temp sensors. One if for the gauge and the other(causing the CEL) is for the ECU. The ECU basically does a resistance check over the sensor to determine if it is functioning. It means that the sensor is bad, or that the wiring to the sensor is bad. I had problems with the intake air temp sensor's wiring causing a short and triggering the CEL, so you might check the wiring close to the sensor. You can also put a resistor over the 2 pins on the sensor(might be a tad hard with the CTS). I believe room temp is close to 1.5-2 kOhm.
 

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Discussion Starter · #3 ·
so in this case it is worth replacing(if it isnt faulty wiring) because its effecting my fuel economy?
 

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Discussion Starter · #4 ·
I have another question. The coolant temp. guage is cold until i stop somewhere and let the car continue to run, then it starts going up. Do you have any idea what it could be?
 

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The coolant temp sensor definitely effects fuel economy...if it thinks the coolant temp is low(what it defaults to during a CEL) the car will never exit the warmup phase and continue to run rich.

Since you mention the car not warming up, I'm wondering if the thermostat is stuck open and the CEL is because of running long term without reaching operating temp. I'd check the resistance on the CTS sensor first.
 

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Discussion Starter · #6 ·
the resistance of the sensor was normal so i took of the battery terminals to reset the cel and it didnt come on. im almost positive its the thermostat but ill investigate further.
 
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