Coolant Temp Sensor lasts about 30 days

curtisleefarmer · Sep 23, 2024

Hello everyone! New to the forum. I have a 2015 Yukon Denali XL with about 210k miles on it. Still runs great for its age/use. The one issue we've had regularly is the coolant temp sensor failing about every 30 days or so. I started replacing them myself and went through a half dozen before we got it into the shop and they claimed it needed an OEM part (sure, makes sense) and a new harness since coolant getting on it was the likely culprit. Well, a month later and it has burned out again. Replaced that one again myself because the shop in our little mountain town is out of business (can't find a mechanic) and it went out almost exactly 30 days later. I've got the new one in, but does anyone have any ideas on what could be causing this? Thanks everybody!

Marky Dissod · Sep 23, 2024

When was the last time you completely changed out all the antifreeze?
If your goal is to keep it for the foreseeable future,
there is a small possibility you may even want to consider a coolant filter, even if only temporarily.

J5races · Sep 23, 2024

curtisleefarmer said:
Hello everyone! New to the forum. I have a 2015 Yukon Denali XL with about 210k miles on it. Still runs great for its age/use. The one issue we've had regularly is the coolant temp sensor failing about every 30 days or so. I started replacing them myself and went through a half dozen before we got it into the shop and they claimed it needed an OEM part (sure, makes sense) and a new harness since coolant getting on it was the likely culprit. Well, a month later and it has burned out again. Replaced that one again myself because the shop in our little mountain town is out of business (can't find a mechanic) and it went out almost exactly 30 days later. I've got the new one in, but does anyone have any ideas on what could be causing this? Thanks everybody!

Original radiator? Do the old ones look corroded or fried or perfectly fine? Have you checked a new one versus an old one with a meter to see what they measure?

My guess (and just throwing out a possible reason, have never seen this happen on any car) is that somehow voltage is in the cooling system and causing electrolysis. Again, Im just throwing out a guess
on this and could likely be way off.

Is your engine ground on the upper right side of the water pump housing in good condition (no broken or damaged wires) and tight?

curtisleefarmer · Sep 23, 2024

Marky Dissod said:
When was the last time you completely changed out all the antifreeze?
If your goal is to keep it for the foreseeable future,
there is a small possibility you may even want to consider a coolant filter, even if only temporarily.

Probably been a while... I will definitely get it in for a coolant flush!

curtisleefarmer · Sep 23, 2024

J5races said:
Original radiator? Do the old ones look corroded or fried or perfectly fine? Have you checked a new one versus an old one with a meter to see what they measure?

My guess (and just throwing out a possible reason, have never seen this happen on any car) is that somehow voltage is in the cooling system and causing electrolysis. Again, Im just throwing out a guess
on this and could likely be way off.

Is your engine ground on the upper right side of the water pump housing in good condition (no broken or damaged wires) and tight?

Not sure on original radiator, as we bought it used several years ago. But the old sensors definitely look perfectly fine with no corrosion or marks. I'm completely in the dark on anything electrical (it's greek to me) so I'll have to get back to you on the other. But I don't see anything with wiring in poor condition if I'm looking in the right place.

2015TahoePPV · Sep 23, 2024

Is it possible you have a marginal ground maybe? Perhaps you have a sensor going out of spec as it gets a few days on it because of the ground? That’s an interesting one for sure.

Geotrash · Sep 26, 2024

curtisleefarmer said:
Not sure on original radiator, as we bought it used several years ago. But the old sensors definitely look perfectly fine with no corrosion or marks. I'm completely in the dark on anything electrical (it's greek to me) so I'll have to get back to you on the other. But I don't see anything with wiring in poor condition if I'm looking in the right place.

I've seen the wiring near the connector go bad on these and cause intermittent issues. It's a common enough problem that some brands of coolant temp sensors ship with a new pigtail that you can splice in. I bought mine for my '07 from Autozone a few years ago, and it came with a new pigtail, so I wired it in. 30K miles later and it's still working fine.

L8T BURB · Sep 27, 2024

This will sound far fetched, but trust me before you go throwing big money and time at this.

Replace the thermostat with a GM genuine part, and also the temperature sensor with a GM genuine part as well. I'd bet the house that the thermostat is the problem, but the coolant temperature sensor being replaced with a GM unit certainly won't hurt. You'll need around a half gallon or so of Dexcool as well.

RET423 · Sep 30, 2024

I would bet you have a bad connection in the the harness at the sensor, bend the tabs a little bit at the sensor connector and plug it back in; if the sensor wakes up you found the problem

Gearz · Sep 30, 2024

I have seen it and fix it. You didn’t say what the codes were but if the coolant is getting into the wiring harness I have seen the coolant make it all the way back to the PCM ( Power Train Control Module ). You have to disconnet the pcm harness and really look at the wiring and pins to the pcm. I had to run new wires and replace the pcm in worst case scenario.

Coolant Temp Sensor lasts about 30 days

curtisleefarmer

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Marky Dissod

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J5races

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curtisleefarmer

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curtisleefarmer

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2015TahoePPV

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Geotrash

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RET423

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Gearz

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