2016 Yukon multiple intermittent issues

[sbrekus]

Hello, I am new here and hoping to maybe get some direction on a problem we are having with our 2016 Yukon Denali. Over the past several months the engine fan will start running at high speed and continued even after the engine is completely shut off for several minutes. It only happened about every six or eight weeks. In between there were no problems.

The engine temperature gauge when the fan was blowing on high read in the low normal range. A couple of times I disconnected the battery, so it wouldn’t run down after the engine was stopped, and either this or just the fan finally stopping seem to reset things and everything worked again. I thought it was the coolant temperature sensor going bad, so I replaced it. No problems for a couple of months and I thought it was fixed but today it happened again.
Interestingly, at the exact same time you could hear the fan go on high, the AC stopped cooling.

On another occasion, the door locks stopped working at the same time as well. They seem to be unrelated, although it makes me wonder now if the ECM or relay module could be the problem, where all these apparently unrelated things might converge. I get no engine lights, and checked an OBD scanner a few times with no errors.

I am hesitant to take it to a mechanic since it is such an intermittent problem and likely won’t happen when they have it in and testing it. Has anyone ever heard of anything like this or anything I can check additionally to troubleshoot? Many thanks in advance of any ideas.

 

[wjburken]

Hello, I am new here and hoping to maybe get some direction on a problem we are having with our 2016 Yukon Denali. Over the past several months the engine fan will start running at high speed and continued even after the engine is completely shut off for several minutes. It only happened about every six or eight weeks. In between there were no problems. The engine temperature gauge when the fan was blowing on high read in the low normal range. A couple of times I disconnected the battery, so it wouldn’t run down after the engine was stopped, and either this or just the fan finally stopping seem to reset things and everything worked again. I thought it was the coolant temperature sensor going bad, so I replaced it. No problems for a couple of months and I thought it was fixed but today it happened again. Interestingly, at the exact same time you could hear the fan go on high, the AC stopped cooling. On another occasion, the door locks stopped working at the same time as well. They seem to be unrelated, although it makes me wonder now if the ECM or relay module could be the problem, where all these apparently unrelated things might converge. I get no engine lights, and checked an OBD scanner a few times with no errors. I am hesitant to take it to a mechanic since it is such an intermittent problem and likely won’t happen when they have it in and testing it. Has anyone ever heard of anything like this or anything I can check additionally to troubleshoot? Many thanks in advance of any ideas.

My guess is you have an issue with your A/C system.

 

[Doubeleive]

door locks are most likely unrelated and is possibly a ground issue-check all grounds
the temperature sensor is directly related to the ac system, if there is a problem with the temperature system the ac system will not operate properly
so either your replacement sensor is not working correctly or has failed or there is a problem with the harness(connector) or harness wiring or even possibly the thermostat is getting stuck or not working properly.
temperature gauge should normally read almost dead center, unless you are doing something extreme in the heat, even if it was -30 deg outside temp should come up and read dead center or a smidge under dead center. it shouldn't normally be lower or higher but could move slightly higher from time to time if you were going up a steep hill or towing something and then return to normal

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[sbrekus]

door locks are most likely unrelated and is possibly a ground issue-check all grounds
the temperature sensor is directly related to the ac system, if there is a problem with the temperature system the ac system will not operate properly
so either your replacement sensor is not working correctly or has failed or there is a problem with the harness(connector) or harness wiring or even possibly the thermostat is getting stuck or not working properly.
temperature gauge should normally read almost dead center, unless you are doing something extreme in the heat, even if it was -30 deg outside temp should come up and read dead center or a smidge under dead center. it shouldn't normally be lower or higher but could move slightly higher from time to time if you were going up a steep hill or towing something and then return to normal

Thank you so much for the input. I checked the wiring for the sensor before replacing it but will again. You gave me some good things to consider. The very sporadic nature of it is strange to me.

 

[sbrekus]

My guess is you have an issue with your A/C system.

Maybe. The fan I refer to is the radiator fan that keeps running after the vehicle is shut off. It seems to think it is overheated, which is why I replaced the sensor.

 

[L8T BURB]

As for the fan issue, which is also tied to your AC and temp gauge issue....

I had this EXACT problem with my 2015 Suburban, and after extensive research online I realized there is not a lot of GOOD information on a true root cause/fix. I will include details of my repair journey which ultimately led me to the solution....

1. Replaced coolant temp sensor w/Autozone sensor (Temporarily seemed to correct the issue)
2. Replaced coolant temp sensor a 2nd time (Autozone warranty)
3. Replaced thermostat AND coolant temp sensor w/genuine GM parts (FIXED)

The only thing I can figure is that the factory thermostat was worn out and was leaking off (constantly staying partially open). This caused the engine temp to never get to normal operating range. This causes the vehicle to enter a "fail safe" mode, causing the fan to run non-stop (including several minutes after shut off), and also causes your AC system to not allow the AC compressor to engage.

If you run the engine long enough like this, you'll eventually get a check engine light and the code will read "operating temp below threshold". This means the engine is unable to get to normal operating range, and is fully entering the fail safe mode.

Trust me...I know it sounds far fetched to believe all these systems are tied together....but I assure you they are.

In short, grab a genuine GM thermostat housing as well as a genuine GM coolant temp sensor. You'll also need about a gallon of Dex-Cool. This repair is quick and easily can be done in your garage/driveway within 30 minutes with a couple of simple hand tools.

Hope this helps!!

 

[09FXSTB]

Hello, I am new here and hoping to maybe get some direction on a problem we are having with our 2016 Yukon Denali. Over the past several months the engine fan will start running at high speed and continued even after the engine is completely shut off for several minutes. It only happened about every six or eight weeks. In between there were no problems.

The engine temperature gauge when the fan was blowing on high read in the low normal range. A couple of times I disconnected the battery, so it wouldn’t run down after the engine was stopped, and either this or just the fan finally stopping seem to reset things and everything worked again. I thought it was the coolant temperature sensor going bad, so I replaced it. No problems for a couple of months and I thought it was fixed but today it happened again.
Interestingly, at the exact same time you could hear the fan go on high, the AC stopped cooling.

On another occasion, the door locks stopped working at the same time as well. They seem to be unrelated, although it makes me wonder now if the ECM or relay module could be the problem, where all these apparently unrelated things might converge. I get no engine lights, and checked an OBD scanner a few times with no errors.

I am hesitant to take it to a mechanic since it is such an intermittent problem and likely won’t happen when they have it in and testing it. Has anyone ever heard of anything like this or anything I can check additionally to troubleshoot? Many thanks in advance of any ideas.

Hi, I am a new Tahoe owner but your symptom recently came up in a search for me....https://www.youtube.com/watch?v=4wd0n9F6--Q coolant temperature sensor.

 

[Fless]

Hi, I am a new Tahoe owner but your symptom recently came up in a search for me....https://www.youtube.com/watch?v=4wd0n9F6--Q coolant temperature sensor.

TIP: if you want an internet link to work in this forum it should be posted without any adjacent leading or following characters (except spaces). Best to put it on its own line.

Aftermarket ECTs are known to fail the accuracy test, so it's best to use OE. Eric O had a YouTube video about that a few weeks ago, where a car wouldn't run the evap cycle due to multiple incorrect ECT sensors.

 

[sbrekus]

As for the fan issue, which is also tied to your AC and temp gauge issue....

I had this EXACT problem with my 2015 Suburban, and after extensive research online I realized there is not a lot of GOOD information on a true root cause/fix. I will include details of my repair journey which ultimately led me to the solution....

1. Replaced coolant temp sensor w/Autozone sensor (Temporarily seemed to correct the issue)
2. Replaced coolant temp sensor a 2nd time (Autozone warranty)
3. Replaced thermostat AND coolant temp sensor w/genuine GM parts (FIXED)

The only thing I can figure is that the factory thermostat was worn out and was leaking off (constantly staying partially open). This caused the engine temp to never get to normal operating range. This causes the vehicle to enter a "fail safe" mode, causing the fan to run non-stop (including several minutes after shut off), and also causes your AC system to not allow the AC compressor to engage.

If you run the engine long enough like this, you'll eventually get a check engine light and the code will read "operating temp below threshold". This means the engine is unable to get to normal operating range, and is fully entering the fail safe mode.

Trust me...I know it sounds far fetched to believe all these systems are tied together....but I assure you they are.

In short, grab a genuine GM thermostat housing as well as a genuine GM coolant temp sensor. You'll also need about a gallon of Dex-Cool. This repair is quick and easily can be done in your garage/driveway within 30 minutes with a couple of simple hand tools.

Hope this helps!!

Update: thank you for this great information. I did replace the sensor again and thermostat and topped off sith Dexcool. I used AC Delco parts (did not see your post before I did it. So far so good, temp gauge reads right in middle now, so I believe it to be fixed. I should have replaced both at first. Thank everyone so much aand I will update after a few more months to make sure.

 

[OutlawJ01]

Hello, I am new here and hoping to maybe get some direction on a problem we are having with our 2016 Yukon Denali. Over the past several months the engine fan will start running at high speed and continued even after the engine is completely shut off for several minutes. It only happened about every six or eight weeks. In between there were no problems.

The engine temperature gauge when the fan was blowing on high read in the low normal range. A couple of times I disconnected the battery, so it wouldn’t run down after the engine was stopped, and either this or just the fan finally stopping seem to reset things and everything worked again. I thought it was the coolant temperature sensor going bad, so I replaced it. No problems for a couple of months and I thought it was fixed but today it happened again.
Interestingly, at the exact same time you could hear the fan go on high, the AC stopped cooling.

On another occasion, the door locks stopped working at the same time as well. They seem to be unrelated, although it makes me wonder now if the ECM or relay module could be the problem, where all these apparently unrelated things might converge. I get no engine lights, and checked an OBD scanner a few times with no errors.

I am hesitant to take it to a mechanic since it is such an intermittent problem and likely won’t happen when they have it in and testing it. Has anyone ever heard of anything like this or anything I can check additionally to troubleshoot? Many thanks in advance of any ideas.

I am currently going through the SAME thing with my 2016 Yukon XL. Replaced the temperature sensor with an AC Delco & within 3 weeks started doing the same thing then replaced with Autozone Duralast brand & now after 3 weeks it started the same thing (no temp reading, & fan blowing hard & long after i shut off the engine) so now I'm thinking maybe the wire or connector is bad. Idk... I hear buy oem (I know AC Delco IS OEM but the first one (OEM ONE) lasted less time than the store brand one (Duralast) so idk if a new wire/coupler will fix it...

 

[Doubeleive]

I am currently going through the SAME thing with my 2016 Yukon XL. Replaced the temperature sensor with an AC Delco & within 3 weeks started doing the same thing then replaced with Autozone Duralast brand & now after 3 weeks it started the same thing (no temp reading, & fan blowing hard & long after i shut off the engine) so now I'm thinking maybe the wire or connector is bad. Idk... I hear buy oem (I know AC Delco IS OEM but the first one (OEM ONE) lasted less time than the store brand one (Duralast) so idk if a new wire/coupler will fix it...

the oem one should have a warranty take it back, so should the duralast. try again..... there are just a bunch of bad ones out there
if it was the connector it wouldn't make it 3 weeks and fail again, if that was the case you could just unclip it and recliip it and be down the road again for another 3 weeks

 

[L8T BURB]

I am currently going through the SAME thing with my 2016 Yukon XL. Replaced the temperature sensor with an AC Delco & within 3 weeks started doing the same thing then replaced with Autozone Duralast brand & now after 3 weeks it started the same thing (no temp reading, & fan blowing hard & long after i shut off the engine) so now I'm thinking maybe the wire or connector is bad. Idk... I hear buy oem (I know AC Delco IS OEM but the first one (OEM ONE) lasted less time than the store brand one (Duralast) so idk if a new wire/coupler will fix it...

The temperature sensor (or the wires connected to it) was never the issue. Replace the thermostat with a Genuine GM one and reset the stored engine code and you'll be good to go. Before you say it, "but I don't have an engine light"... when the fans start running like that and temp drops to zero, at that moment, the ECM stores a code of "coolant temperature below threshold".

Replace your thermostat, top off with Dexcool, use a pocket scanner or similar to clear the stored codes and you'll never have another issue. The thermostat fails over time and stays stuck open, not allowing engine temp to reach the optimal range, hence causing the fail safe mode to engage.

Also if you have your original temp sensor, throw it back on there just to show the members here that it never was a temp sensor issue. While I understand both the temp sensor and thermostat can fail at some point, the root cause is the thermostat. People get confused because of the temp gauge dropping to zero and automatically want to point to the temp sensor. Just search the forum... I haven't noticed a single person with these symptoms who replaced thermostat and had continued issues.

 

[Doubeleive]

this very well could be the case as well, both are known to have issue's

 

[Joeltz]

Exact same problem on my 2015 Tltz Managed to snap small hose barb off Napa thermostat housing The gave me a replacement N/C Thermostat fixed exact same problem ! Note once back together and run around the block Recheck the Dexcool level !