External temperature sensor

[Fred77]

Hello.
My 2007 XS diesel showed a temperature reading on the small LCD screen of 0 degrees and the snowflake was on the dash when it was 20 degrees outside. I disconnected the sensor and it showed 10 degrees on the LCD with no sensor fitted and stayed at that.
Thinking it was the sensor I purchased a used one from eBay that was said to work. I installed that but the temperature still reads 10 degrees, (and its a warm day!) Assuming the “new” one is OK can anyone tell me what the problem may be? I have checked the ohms reading on both sensors across the two pins and they both are showing around 31 ohms. Is that a good reading or are they both duff?
Incidentally I have removed the fuse for the Webasto heater to stop that coming on. Could that affect things?

Any help appreciated.

Cheers,

John

[Old Peter]

Welcome to the club, John.

I had the same problem las week, after we had a period of cold weather.  The snowflake remained on the dashboard when it was getting quite warm, I had heard that some diesel engines stay warm for a much longer period than petrol engines, so I assumed they would also stay colder longer.

As I had not used my car for a couple of days I guessed that it might rectify itself and as I was going on a drive that would take half an hour each way I thought I would do nothing. The snowflake disappeared and the temperature rectified before the half hour on the outward journey was up.

It could have been the Webasto Auxiliary heater not coming on that was the problem, and putting the fuse back is worth trying.

Regards,

Peter.