MAT sensor resistance question

[Gjk]

Does anyone know what the resistance should be of the MAT sensor when cold? Car is a 1991 turbo se.

[Escape]

The MAT sensor is NTC, which means a low temperature will give a high reading and vice versa. The manual says 100 kOhm at -40°C and 185 Ohm at 100°C. Ambient will be a few kOhm. I can check tonight if you want (and I don't forget...).

Filip

[fjmuurling]

The resistance values for the various MAT sensor temperatures is also given in the EMH manual.

[Gjk]

I have just hooked my sensor up to a multimeter and it’s reading 3.54 kOhm. The indicated ambient temperature in the room is 19 degrees (household central heating thermostat).

does that sound like a reasonable resistance for the temperature?

I would be interested to see what @Escape gets, only if it’s not too much hassle.

[fjmuurling]

According the EMH Manual the resistance of the MAT sensor at 20 degC is around 3400 Ohm.

So your measured value sounds right.

Be aware that the sensor resistance is not lineair with the temperature.

[Gjk]

Thanks @fjmuurling. I did not realise the relationship between resistance and temperature was not linear.

[Escape]

I got 3.955 kOhm at 16.6°C, very much in line with what you found. At lower temperatures the resistance rises rapidly, as with most sensors.

I had a quick look through the EMH but didn't find a detailed temperature/resistance graph.

[Gjk]

Thanks @Escape, most kind of you to cram yourself into the engine bay on your SE! Much appreciated.

[Escape]

Anything to help out a fellow Esprit owner. 😉

And it really wasn't too hard to reach the sensor...

[Gjk]

Ah-ha, I see! Much better access! I’m now suffering from workshop envy….  😢

[fjmuurling]

3 hours ago, Escape said:

I had a quick look through the EMH but didn't find a detailed temperature/resistance graph.

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