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Golf mk7 / Strange heating issues
« Last post by Ssharp on 10 December 2025, 19:45 »Hi all,
I have decided to join the forum to see if I can get any help or recommendations with some strange heating issues going on in my gti. I have a 2013 mk7 gti currently on 88,000 miles, I’ve owned it since August and loved it. However since it has got colder I started to notice the car was giving out lukewarm air at most, even after running for a bit. I checked the header tank and saw there was no silica bag, which made me think the matrix was blocked up. I got the matrix replaced which made no difference. I then moved onto looking at the heater control valve, which when pulled off and I tried to blow through it, it was seized shut. We then replaced that, which was from a breakers yard however the valve didn’t seem faulty and there was no resistance when trying to blow through this one. This made a small improvement however the car is still taking ages to warm up! It’s normally not until I get to work (20 min drive) that any heat comes through whatsoever, but when it comes through it gets very hot very fast. I’m also questioning whether it’s when I slow down or come to a complete stop that the heat starts to come through too, as I have to queue to get into work. I have had the car scanned after the matrix was done and the codes P275300 and P011800 came up, but this was likely due to the coolant being drained, as I’ve had it rescanned and the codes aren’t present anymore. In the past week now, when the heating/ac is completely off, it now appears to be giving out more heat when it is actually on (I don’t know how!). My only thought was that it may be a coolant temp sensor as it seems to get up to temp pretty quickly and doesn’t really fluctuate from 90 even when being driven hard. It’s also worth noting the water pump hasn’t been replaced yet and there is very very minor residue around it. Other than that I am stumped. I appreciate that this is a very long post however I figured this would be the best place to come for help, therefore any is really really appreciated.
Cheers,
Sam
I have decided to join the forum to see if I can get any help or recommendations with some strange heating issues going on in my gti. I have a 2013 mk7 gti currently on 88,000 miles, I’ve owned it since August and loved it. However since it has got colder I started to notice the car was giving out lukewarm air at most, even after running for a bit. I checked the header tank and saw there was no silica bag, which made me think the matrix was blocked up. I got the matrix replaced which made no difference. I then moved onto looking at the heater control valve, which when pulled off and I tried to blow through it, it was seized shut. We then replaced that, which was from a breakers yard however the valve didn’t seem faulty and there was no resistance when trying to blow through this one. This made a small improvement however the car is still taking ages to warm up! It’s normally not until I get to work (20 min drive) that any heat comes through whatsoever, but when it comes through it gets very hot very fast. I’m also questioning whether it’s when I slow down or come to a complete stop that the heat starts to come through too, as I have to queue to get into work. I have had the car scanned after the matrix was done and the codes P275300 and P011800 came up, but this was likely due to the coolant being drained, as I’ve had it rescanned and the codes aren’t present anymore. In the past week now, when the heating/ac is completely off, it now appears to be giving out more heat when it is actually on (I don’t know how!). My only thought was that it may be a coolant temp sensor as it seems to get up to temp pretty quickly and doesn’t really fluctuate from 90 even when being driven hard. It’s also worth noting the water pump hasn’t been replaced yet and there is very very minor residue around it. Other than that I am stumped. I appreciate that this is a very long post however I figured this would be the best place to come for help, therefore any is really really appreciated.
Cheers,
Sam
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