Transmission Temp. Sensor

reardiff · July 12, 2023

So I appear to have the dreaded faulty Trans Temp sensor. Very erratic transmission temperatures, shows as low as 44 degrees each morning even though it's maybe 75 degrees at the lowest in the garage and recently had the engine light come on with p0700 & 7011. I know the issue and the fix for it but have a few questions.

1. There's special coverage for this exact same condition for 2016's with the 6.2 and 8 speed but appears to be limited to 2016 model years only. Why? If the same issue is happening (same engine/transmission combination) for my 2017? I assume there's nothing I can do about this but will certainly ask the dealer when it goes in on Friday.

2. It's coming due for a full flush/fluid exchange. But the pan has to come off to replace the sensor/wiring harness. Is it still worth paying what I'm assuming is close to $200 for a full flush even though they already have to drop the pan to replace the sensor, or do I just let them fill it back up and call it good, knowing there's still plenty of fluid left that didn't get replaced?

3. Anyone know what the cost for this is? It's a 2017 but outside the powertrain warranty by about 9 months and 12,000 miles. It doesn't sound like a cheap fix. Which is why I'm curious about item #1.

4. Is it safe to drive this way? I assume so but not sure what all the trans temperature readings impact?

Going to the dealer on Friday but hoping to gain a little more knowledge on the questions above from anybody has may have gone through this already.

jrmcswain · July 12, 2023

The repair costs about 200 with fluid. The dealer quoted some stupid g

High price, so I did it myself.

It's probably not good to keep driving this way. The temp is used to determine shift points and pressures. There was more clutch material in the fluid than I would have liked.

newdude · July 12, 2023

Don't let them flush it with some random @ss fluid!!!!

Mobil LV ATF HP Blue Label ONLY! GM # is 19417577, and they should have plenty of it in stock in one form or another.

GM has a fluid exchange method for the 8 speed shudder which is what GM calls a "triple flush". Takes 16-20qts to do the job. They hook up a cooler flow machine direct to the transmission for filling purposes only, and then hook a hose with a cooler line adapter to the transmission. 4 quarts out and shut it off, add 4 in and run it then drain 4 out and repeat to get as much of the old stuff out.

Being the pan will be down, they will have added 6-8 quarts of fresh fluid back in, so if you wanted as much changed as possible, they'd have to run another 8 through it using the above method.

This can be done DIY but would obviously involve dropping the pan multiple times.

reardiff · July 27, 2023

To report back, the dealer confirmed it was the trans temp sensor, but for some unknown reason there's special coverage for 2016 but not an identical vehicle for 2017. Same engine, transmission, etc. Total cost was $923 which included replacement of the sensor/harness and filter. The paperwork has 12 quarts of fluid on it which I doubt they actually used by just dropping the pan. Decided to skip the extra cost of a full flush and get the use out of the 8 quarts or however much the re-filled it with and then maybe do a flush in another 25k miles which will be just about 100k miles, at least it's got a new filter now and shouldn't have to drop the pan again later.

Andrew Boris · January 7

Good morning.

'17 Silverado 95k miles on it.

This code just threw on my truck yesterday.

Still runs perfectly fine and the transmission temp seems to be somewhat normal.

I was going to attempt to replace the sensor and harness myself because my truck is out of warranty and I don't believe there is a recall on the 2017s.

Two questions

1) Can anyone provide some type of feedback on the difficulty of this replacement.

2) I have searching and cannot find the exact sensor or part number to order.

Any and all feedback is appreciated. Thank you

reardiff · January 18

Had this done back in July. Noticed the temp display very erratic then eventually the light would come on and off with codes P0700 & P0711. You have to replace the entire harness, local dealer did it for $923 which includes a new filter. This is almost all labor. Parts (Harness, Filter, and Fluid) only came up to about $200, rest is all labor. Part number for the new harness is 24046895.

As far as difficulty of replacement, there's plenty of you tube videos out there. Doesn't look too difficult as long as your comfortable removing the pan and valve body. What I don't understand is why there is special extended coverage for this exact same issue/part through model year 2016 but not 2017?