Hi I'm new to all this forum not sure weather I have posted in the right place 

 

I have a focus 2011 1.6tdci my temp guage it perfect with driving sits at normal temp and don't move as soon as I put my blowers on it drops until it's gets to the bottom of the gauge any ideas 

 

thanks 

Using the heater will draw some of the engine heat away so a little drop in temp is pretty normal especially in the colder weather. I suspect your thermostat may need replacing if the temp gauge is dropping that low. what's your MPG usage like? Do the heaters get hot enough or only lukewarm?

Mpg ent that good if I'm honest blowers are loverly and hot no matter what the temp gauge is showing! 

 

It dont happen when I'm driving only when the car is on idle at traffic lights the gauge till go from 88 right to the bottom is about 45 seconds 

14 hours ago, Matthew4880 said:

blowers are loverly and hot no matter what the temp gauge is showing!

It dont happen when I'm driving only when the car is on idle at traffic lights the gauge till go from 88 right to the bottom is about 45 seconds 

I reckon it could be the Engine coolant temperature (ECT) sensor in the CH.

If the heater stays hot when the gauge drops right down, it almost has to be the gauge or ECT. It is normal for temperature to drop a little when idling, but to the bottom like that can not be a real reading.

Also the ECU gets this reading, and could be make the mpg worse if reading wrong.

You can do a gauge sweep test to check the gauge. I think you hold the mileometer stalk in while turning ignition on, and step through some menu stages. It may also display the engine temp in deg C. And battery voltage, though this may be a bit inaccurate. See:

If the gauge is ok, but the odd readings continue, I would just replace the ECT.

Thanks for the reply I have been thinking no one would help! I have replaced the temp sensor as that is what the gargue for it was but still nothing! It's a real mind blower this one 

11 hours ago, Matthew4880 said:

I have replaced the temp sensor as that is what the gargue for it was

Ummm, that was the best possibility. Though I am not quite sure about the gargue bit!?

Worth trying the dash test mode, to see if it has a display in deg C.

Then I would get a temperature meter, maybe something like: http://www.ebay.co.uk/itm/TM-902C-K-Type-Digital-LCD-Thermometer-50-C-to-1300-C-Thermocouple-Sensor-Probe-/322274501986?hash=item4b090ea562:g:JH0AAOSwmfhX6igO

And use it to measure the CH temperature near the sensor, just to be sure the real temperature is not dropping badly. It has a small sensor end that can be taped to any surface. Then do further tests on the car sensor, like measure its resistance with a multimeter at various temperatures. I am not sure of the actual values expected, but I know how a thermistor should perform, and could probably tell from a table of readings if it was mis-behaving. Replacements can be faulty.

I guess this problem is annoying rather than critically important, so investigating it may be a lowish priority. But if it is affecting fuel economy, as is possible, it could be worth a bit of effort in the long run.

 

I have done the dash test and it shows what the temp gauge shows I have tried it 3 times when the temp gauge shows diffrant I will get something to test the temp with and will update and let you no what the outcome is many thanks for the replies