For replacing the temperture sensor on a 1.2 16v '98 Haynes says that the whole system has to be drained, but I can hardly believe it. Is it true? Do I really have have to drain the coolant, replace the sensor and fill it up again??

I think that the hayes is right. Because the sensor is in the coolend. So it's rether logical that the coolend has to be draind. Sorry for my bad englis.

Hope this helps.

Thanks Mixter, but what about the following theorie.

When I make the filler cap air tight with duck tape or whatever, it should create an air lock, so when I remove the sensor, no air can come in and therefore no coolant can come out, ok ok maybe a little bit, all with a cold engine ofcourse.

Anyone else tried this before?

You'll lose some coolant.

Replace the sensor, top up with coolant, bleed.

Bauk said:

For replacing the temperture sensor on a 1.2 16v '98 Haynes says that the whole system has to be drained, but I can hardly believe it. Is it true? Do I really have have to drain the coolant, replace the sensor and fill it up again??

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just unscrew temp sensor and quickly stick your finger in the hole so it stops dripping out and put new sensor in, amount of coolant lost is minimal



interesting temp sensor is on other side compared to 8v

thats a more modern engine, the fact it has a knock sensor is a dead give-away, also coil on plug leads and plastic inlet mani and manicat.

On the early 16v engines the sensor is in almost same position as that except the lower part of the inlet mani is metal and not plastic. This is not the other end to an 8v though, its on that side of the inlet mani on an 8v too. What is the opposite side is the sensor for the temp gauge, on the 16v its near the thermostat and the 8v on the rear of the head at other end, which is not so on that engine by looks of it - some of the new engines have the gauge sensor actually as part of the thermostat.

As for the original question, no need to drain no. Just be quick so you don't lose loads and then top up and bleed as suggested already. Although if the coolant hasn't been changed recently it might be a good time to flush the system clean and refill with fresh stuff, hows the coolant looking? clean or all murky and brown?

I just drained it partly. Enough to let the level just below the sensor and then replaced it (quickly, because I drained just a bit too little)


Ow, and I lifted the left side of the car, so that I had to drain less than when the car would stand with 4 wheel on the ground.


Just refill afterwards, remove airbubbles and you're done.


Together with the sensor I replaced the thermostat. Not that expensive and only once the job for the case the problem is the thermostat instead of the sensor. They ly next to each other.