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coolant temp sensor 1990 SE


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Hello folks, Very long time since I last posted. Car is trouble free.

It looks like I need to replace the temp sensor under the intake manifold. The one that sends data to the ecu for fan control.

I will have the chargecooler pump and oil filter out soon and would like to know if the sensor is easy to get at with these part removed.

The reading that i get at the moment from the sensor is minus -23c  , 4.3 volts. Then sometimes jumps to correct temp but voltage stays at 4.3v

Any info is appreciated..  Thanks David..

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The temperature sensor is an NTC resistor, so a low temperature reading corresponds to a high resistance. This is often caused by a bad connection, so I'd start by checking that.

As an aside, the ECU uses the temperature reading primarily to adjust the fueling (from cold start to normal operating temperature), switching on the fans is just a secondary function. So it's important the sensor works correctly so the engine runs as it should.


I have made many mistakes in my life. Buying a multiple Lotus is not one of them.


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I changed mine only a couple of months ago and struggled to work out how to access it but once I'd worked out exactly where it was, I found I could JUST reach it from above by reaching under the plenum. Starting the thread on the new one was with finger tips at full stretch but once started easy to tighten with a socket on an extension. If your arms are shorter than mine then I'm sure removing the plenum cover would give far easier access. 

Others may have easier ways but that wasn't difficult. 

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