[GM Lifer]

Originally Posted by 2K16SummitSS

I can promise you it is the thermostat sticking open, causing your car to go into safe mode because it actually reads too low of a temp consistently. Temp gauge drops to 0, fans kick on to 100%, rev match won't work (if you have manual). I went through this multiple times over the course of a year, disconnected and reset, replaced the temp gauge, until I was finally told it was the thermostat causing all of my issues. I have seen this exact problem pop up for many over a few different forums/facebook pages, so I'm guessing our thermostats aren't so great. 10 minute install, cheap and easy fix. Thermostat is right on the top of the engine. If you're under warranty and don't feel comfortable doing it yourself, point the dealer in that direction.

I think you nailed it. Engine temp gauge is pegged at the bottom, with no temperature reading whatsoever. I think the car's in safe mode, as the fan runs incessantly and the air conditioning won't work. It's almost like safe mode presumes the car is overheating and prepares for a worst-case scenario by constantly running the engine fan and disabling heat-inducing accessories like a/c.

[cellsafemode]

well, not almost like. exactly like.

what's annoying is that the ECM has oil temp to cross-check a low coolant temp and make a more educated decision and more accurate error code thrown.

ie, if coolant temp sensor showed unexpected data, it could fall back on oil temp and say "hey, oil temp is fine or even low but oil level is good and oil pressure is good. T-stat must be stuck open ...lets not be an annoying pain in the ass and still let the user use the AC since this is an issue that wont damage the car really. "

[Bumbleboy92]

Originally Posted by cellsafemode

I wish it was a simple install for the lgx. They put that stupid thing right in the valley underneath the intake manifold underneath a hard oil/trans return line below the hose level of the radiator.

So you have to take the intake manifold fully off, then fabricate your own wrench most likely to get at the thermostat bolts and bend or remove the return line to take it off, all while you're dumping coolant (or having to partially drain it prior to working).

Pretty sure the designer of that piece of crap has family in the dealership business. It's unnecessarily difficult for something that seems fairly failure prone after 5 years of age.

This little thing, thought I could replace mine when I was swapping to ported intake manifold. I’m still trying to find a wrench that’ll fit down there near me :(



I’m constantly unplugging and reattaching the negative on the battery, I’m hoping my sensor replacement will fix but if not then guess I’m buying a thermostat and hoping that isn’t as bad to reach

[GM Lifer]

Originally Posted by cellsafemode

well, not almost like. exactly like.

what's annoying is that the ECM has oil temp to cross-check a low coolant temp and make a more educated decision and more accurate error code thrown.

ie, if coolant temp sensor showed unexpected data, it could fall back on oil temp and say "hey, oil temp is fine or even low but oil level is good and oil pressure is good. T-stat must be stuck open ...lets not be an annoying pain in the ass and still let the user use the AC since this is an issue that wont damage the car really. "

Amen to that. But speaking of error codes, I don't even have a check-engine light on.

[cellsafemode]

Originally Posted by GM Lifer

Amen to that. But speaking of error codes, I don't even have a check-engine light on.

correct, it doesn't trigger an SEL. But the code is there when you check with a tool, resetting the code gets everything back to normal ...until the self-test fails at some point again due to not reaching the target temp.

[cellsafemode]

Originally Posted by Bumbleboy92

This little thing, thought I could replace mine when I was swapping to ported intake manifold. I’m still trying to find a wrench that’ll fit down there near me :(



I’m constantly unplugging and reattaching the negative on the battery, I’m hoping my sensor replacement will fix but if not then guess I’m buying a thermostat and hoping that isn’t as bad to reach

the sensor is almost definitely fine.

get a simple odb2 code reader/resetter (they're like 15-20 bucks) and reset the ecm codes. You'll see the temp reading fine again if the sensor is fine.

The t-stats fail open and it seems to be fairly common once the car is 4-5 years old.

But to change the sensor, you would probably do yourself a favor and take the t-stat off to reach it anyway.

[2K16SummitSS]

Sorry to hear you LGX owners got the shaft on t-stat placement. Reminds me a bit of alternator placement on the 4th gen LS1... and bolt placement on the steering rack...and number 8 plug...man I have such a love/hate for F-bodies lol

[LT4Greg]

Originally Posted by 2K16SummitSS

Sorry to hear you LGX owners got the shaft on t-stat placement. Reminds me a bit of alternator placement on the 4th gen LS1... and bolt placement on the steering rack...and number 8 plug...man I have such a love/hate for F-bodies lol

Oh yes how well I remember working on my 1998 SS! It was a pain in the ass most of the time.

[GM Lifer]

Originally Posted by cellsafemode

correct, it doesn't trigger an SEL. But the code is there when you check with a tool, resetting the code gets everything back to normal ...until the self-test fails at some point again due to not reaching the target temp.

Finally got a check-engine light this morning. Taking the car in on Monday.

[2K16SummitSS]

Originally Posted by LT4Greg

Oh yes how well I remember working on my 1998 SS! It was a pain in the ass most of the time.

I had a 2000 SS from 88k to 233k...fun times. I somehow forgot how fun, and bought my wife a cammed WS6

[MANNAXMAN]

Had the fans come on again today and now have a CEL. Watched a video on how to replace the thermostat. Seems simple enough. Anyone have the part number for the OEM thermostat? NOT the thermostat housing, just the thermostat by itself.

[lt4camaro]

Low coolant temp is whats doing it, swap out the Thermostat with a GM replacement.

[MrCharlieV]

Had the same issue on my 2016 RS 33k miles.
Changed the thermostat and that fixed the problem.
Hope that helps.

[bobo1erv]

its not the thermostat, just change it on a 16' 2ss convertible 6mt and it still happened. next thing im going to try is the temp sensor. put my scan tool on it temp reading was different from the gauge