coolant temperature sensor came out

Driving to work this morning, and the low coolant light came on and started beeping. Pulled over and saw the sensor was out. I watch the temp with torque app, it didn't overheat or anything to cause it to get pushed out.

Is this a common problem?

EDIT-2000 beetle alh

If it's like the coolant sensor on other VW engines, it should be held in by a U shaped plastic clip, not just from being pressed in with the O-Ring.

If you google for a replacement sensor, you should see most are sold with the O-Ring and U shaped clip

Probably the clip fell out.

My wife's Vert did the same thing. The plastic clip twisted and let it slide out and start leaking. Luckily it was just down the street from our home.

OK. Looked at it for a couple minutes in the rain waiting for the flat bed. I will order a new sensor, oring, and clip.

I lubed the new oring with some coolant and put the sensor in and new clip. Refilled with coolant, let it idle for 10 minutes and no leaks. Went for a drive, came back, and its leaking bad and it is really loose in the housing. Do the housings go bad?

EDIT-the original clip was still on the housing, a little twisted.

Did you check if there were any pieces of the old o-ring inside the hole?

Either one side of the clip got pushed out or I never got the one side in the slot correctly to begin with. I thought I was pretty careful about it. Put the clip back in and there was a definite click as it seated that I didn't remember from the first time. So I guess the clip was just in wrong. Went for a hard drive (close to home), no leaks. I guess I am good to go. The complete oring was still on the original sensor when it came out.

For what it is worth, if you're out away from home, etc., and discover a small coolant leak, loosen the rad cap so the system will not hold pressure. This will allow you to hobble home or to a guru for help.

Without all the details, I drove my ALH Vanagon over 10k miles without the coolant system being pressurized. I was pulling a camper and running AC, thus plenty of challenge for the cooling system. I never had an over-heat issue, not even close!

Yeah, that little horse-shoe clip can be tricky! Glad you got it on !

Yeah, that clip also has a history of fatiguing over time and then breaking, which of course leads to a nasty coolant leak. The other thing that I've found, both on my car and on two separate friends with MK4s, is that around the 5 year mark or so the O-ring starts seeping or the sensor fails on one circuit (usually not on both at once.) I've added this one to the "do it when you do the timing belt" list, since the sensor is reasonably cheap and since you already have to drain the coolant you won't make a mess doing it then.

Supposedly VW improved the sensor some time back, but I had one of the improved ones (the new color) that ALSO failed at ~5 years, so..... yeah. I just change it when the timing belt is done.