99problems Posted April 23 Report Share Posted April 23 I changed the coolant temp sensor from genuine to aftermarket (green one) about 2 years ago as needle was jumping 0-90-issue resolved. 1 year later I noticed coolant leak from the sensor, changed for a new (aftermarket)sensor as I couldn't get the o ring separately-seal fixed but now only going 70c on the gauge. Foolishly I had binned the old working one but I thought I just had a faulty sensor so got a new one under warranty, changed this still the same issue. Was going to put a genuine temp sensor in place however I thought I would just change the thermostat too as it was old & maybe I had gotten unlucky for both issues to happen at same time, fitted new non genuine thermostat in (I know!) & the gauge is now going to 90c on the dash after say 7-10miles-Issue fixed I think. The 1st long run I went (150miles) the 1st 20miles the gauge is stuck to 90c as it should, after that it drops down to 70 & even goes below so I am thinking the coolant temperature sensor is faulty however at the end of the journey I check the temperature of coolant in the expansion bottle using the Mrs cooking thermometer & its 67c. Now when doing short journeys its not getting to 90c as it was when I had just changed the thermostat, the hottest i have gotten the coolant in the expansion bottle is 72c & I the range of the sensor is supposed to be 75-92c from what i can find online (so it sits at 90 on gauge). So is the thermostat stuck open & causing issues or do i have a faulty sensor? Can't find my infrared gun to check temperature of coolant at sender location which is helpful🤦♂️. Before I go waste £65 on a genuine coolant sensor is there anything else it can be or have I missed something? Car is still running fine & giving heat through vents. Cheers. Quote Link to comment Share on other sites More sharing options...
Skezza Posted June 9 Report Share Posted June 9 It kind of sounds like another faulty thermostat. Mine's just gone, very similar symptoms. Mine wouldn't get anywhere near 12 o clock on the dial, where it has always been before. It blew lukewarm out of the vents. If I sat in traffic, it might get up to 12 o clock. I never could tell if it was running rich or whether the engine was clever enough to compensate, but I think it probably did run rich constantly as it thought it was excessively cooling the engine. Just replaced mine as well. Pretty stupid job on a Lupo GTI. The thermostat housing is right next to a gear linkage which leaves you very little space to work in, unless you start moving or removing crap. 15 minute job becomes an hour job. Quote Link to comment Share on other sites More sharing options...
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