Temperature problem

[Gillsfan]

Hi

 

I've just bought a 05 reg focus mk2 1.6 zetec climate. There is a small problem with it. The temp gauge seems to under read, it stays at about 60 degrees when drive rising if stood still. I've run the dash diagnosis thingy and the temp is approx 30 degrees higher on that. I've plugged my blue tooth fault code reader which gives a temp reading, which gives a 3rd reading approx 10 degrees higher then the gauge. I'm also pretty sure the fan isn't coming on. Is there a temp senderived that feeds the gauge and the fan? Anyone any idea what the fault could be?

 

Many thanks in advance 

 

Steve

[Tdci-Peter]

3 hours ago, Gillsfan said:

Is there a temp senderived that feeds the gauge and the fan?

Yes, there is only one sensor, in the cylinder head. It is connected to the pcm (engine computer), and the IC (Instrument Cluster) gets its readings from the pcm over the main CAN bus.

The gauges on these cars are sometimes configured to simply read low-normal-high, with fairly arbitrary needle positions.

The difference between the code reader & the dash display is a bit odd. If the code reader can be trusted in other ways, then I would use that one, as it should get its data direct from the pcm.

Thermostat opening temperature is usually 80 to 90C, and it should stay at this temperature until the radiator is hot all through, then start to rise, with fan coming on at about 100C.

The code reader / diagnosis system I would trust most, is Forscan.

[Gillsfan]

Peter thank you.

My biggest question is why the big difference between the dash led test page (see photo) and the gauge. Would they not get the reading from the same sensor? I'm confident that the fan isn't coming on. I've just been into town to collect a pizza. Put the dash test screen on once I'd collected it and had a high temperature 112 degrees which fell as I drove. The rate at which it fell increased the faster I went.