aurieg

2016 Z06 Manual with Z07 package here, no mods (that I know of). 35,000 miles or so.

So the car reeeallly seems to not like any cold below 50F. Here's what happens:
* Cold start when car is dry or wet (after rain), it's 50-55F or colder out.
* I jump on the freeway in Eco or Tour mode. Steady freeway speeds. Has once happened on backroads with steady speeds.
* After about 15-20 min, the water temp shows 0 degrees and fan goes on max, car goes limp mode, redline goes back to 5k with yellow line around 3.5-4.
* In a couple cases, the rear transaxel temp ALSO shows 0 degrees and I get a Service Rear Axel warning.

Typically the car needs about a day to recover, where the fan runs at full always and ends up killing the battery

I've recently discovered tried-and-true way for kicking it out of limp: after about 10 minutes of driving, put car into Sport and gently rev it to 5000rpm or so. The limp mode / 100% fan / rev limit disappears within 1-2 minutes when done right.

One dealer says this is a water temperature sensor failure, but since the rear diff has similar problem, could it really be a wiring problem with the car?

Related: the carbon brakes "Brakes Worn" flashes basically every start. I had one dealer try to fix it, they I guess jiggled a cable for $100 but still the warning every start. Dealer says pads / disks look fine.

DTC codes that I've seen stick for a while:
P0128 "Coolant thermostat"
P015B "heated O2 sensor"
P050D "cold start rough idle"

No rear axel codes tho?

Anybody have symptoms like this before? I am weary of having a dealer spend a lot of time on it because the car is out of warranty (2016) and they already failed to fix the brake warning.

Is it common to need to replace temp sensors on Z06 / Z07 for water and maybe rear axel?

Thanks for any help!

TurdsOfMayhem

As lonnyh1 stated, check your battery. My battery suddenly went bad and was throwing damn near every "service" message possible including the anti-theft system so I couldn't start the car.
New AC Delco Gold battery, everything is back to normal.

boraxman

Thought I was facing an expensive gear position sensor replacement, new battery and issue rever returned. Good luck!

aurieg

alright alright! new battery seems fair, I got the car used so it's probably indeed overdue. The "Brakes Worn" thing started well before everything else, which is why I thought possible wiring issue. It's true that cold weather is bad for batteries and I really only have these problems cold, tho the car does start just fine on the current battery?

madrob2020

Seen quite a few posts about the carbon brake sensor wire(s) can become loose where they seat in the pads causing the pad warning. Someone else with actual knowledge of them having this throwing a code will jump in.👍

v26278

Agree on the battery. A lot of the sensors communicate by sending or receiving reference voltages. A weak battery can affect the voltage.

The brakes warning is also sent by a brake wear sensor, so if the brakes look good then a sensor issue is the next suspect. With all those other issues that also involve sensors, then the battery is the prime suspect.

Put a high quality new battery in and see wgat happens. I’d recommend the AC Delco Gold with the 42 month warranty. It may not end up solving the issue, but it’s highly likely and relatively cheap. It’s the first thing I’d do

Thomasmoto

I will. I had the worn brakes issue in my 19 ZR1. It turned out to be a bad brake pad sensor and they have a new flash update for this issue as well.

Bill Dearborn

Your car doesn't have major wiring issues. That is just the way that modern cars that are built as systems of systems work. Each subsystem requires proper performance of other subsystems and if the other systems aren't working properly the affected subsystems will set a Service Me message which basically says there is a problem but it's the other guys problem. The diff service message is more than likely caused by the engine temperature issue. The eLSD electronics can't properly manage the diff unless the engine temp is where it is supposed to be. So a bad thermostat can cause the diff to set a warning that it can't operate until the other problem is resolved. It is all pretty simple, Of course, a bad battery can cause many electronic issues and that is the first thing you should check but I suspect you have a coolant temperature sensor problem since the other symptom of a coolant temp sensor problem is the fan running all the time. If you do a search on the forum you will find many posts about the temp sensor going bad, registering no temp and the fan running at full speed since the ECM doesn't know what temp the engine is so it provides max fan speed.

The brake wear sensors are wires that pass through phenolic pills mounted on the inner brake pads of the CCM Rotor cars. These pills can be mounted improperly on some pads thus will wear through faster than they are supposed to. The sensor is supposed to wear down as the rotor touches it and eventually the rotor will break the wire inside the pill causing the brakes worn message. This can happen at each of the wheels so all 4 inner brake pads need to be inspected and the pills mounted on them need to be inspected to see if the the rotors have worn through the wire. Other points of failure can be where each sensor connects to the car harness at the cradles and where the circuit attaches to the EBCM.

Bill

StevieB

"Each subsystem requires proper performance of other subsystems"
and on and on and on.
I have a C5 and was searching for info about EBCM and ended up here. It looks like there may be SO MANY
reasons for various problems. It makes me think that I should get rid of my car
with 1,000 times less tech. Maybe anything C1-C3, no newer. Or get an old Ford station wagon
with some wide tires to look high performance. I guess my dad was right when I was a kid and he
got a 62 Ford station wagon, no options. He said, "the more things on a car, the more that can break"
Looks like maybe he was right.

aurieg

Bill: Thanks for the details about the brakes. Pretty sure the dealer just looked at the pad thickness and was like "yelp it's fine!" haha. I didn't know the sensors themselves were a durable part!! I'll keep that in mind when I need to swap pads.

Installed a new battery! And wow it certainly starts better! Also, need to do some more thorough testing, but MPG on a common route went from 24/25 -> 27/28 (!!!!!) So maybe that O2 sensor fail was indeed due to battery? And it was perhaps the primary O2 and not the cat O2?

All my codes disappeared after battery swap, though maybe that's expected. The "Worn Brakes" still fires on start-up, as pesky as ever! So maybe it's indeed a failed physical sensor instead of wiring. Car is 2016 and I can believe GM miffed that part, they miffed the wheels after all! (I'm already on one cracked rear, likely one cracked front)

FWIW (lazyweb lurkers!) These two battery swap videos helped me the most:
* (more complete, note using screw driver to un-do plastic clasp for red side)
* (note the red side you can leave stuff screwed together like this one)

I got the better of two Interstate battery options at local Costco for like $200-ish out the door. Hope it lasts a few years at least! Then I might go Anti-Gravity if I got the money.

aurieg

Long drive and all the aforementioned problems came back So new battery didn't fix things that might have been electrical gremlins

lonnyh1

Your alternator could be the problem, if it isn't charging the battery a long drive would drain the new battery. You might want to have the alternator tested just to confirm, also double check the battery cables, if they are loose the battery will not charge correctly. The brake wear sensors may be a separate issue as Bill stated.
Good luck

aurieg

Ah interesting idea! But the thermostat usually fails within about 15-20 minutes of cold start to freeway driving. I wonder if freeway / hypermiling does put the alternator / electical into a borderline state.. i.e. the car only wants to be driven hard T_T

I also had "stabilitrack" / "service rear axel" again on cold start while the car was at high altitude / 50F, and the slip control started getting reaaaally aggressive, like 0.5g on perfectly dry good pavement it would fire. So another thing to make me question electronics, as these things seem to be correlated with cold start at cooler temperatures.

I think I'm finally gonna get the thermostat swapped, will report back if that repair surfaces anything interesting.

Red86Cfour

If you're gonna change the thermostat might want to change the coolant also, its real easy to drain and fill.

aurieg

Yessir fluid flush is in the cards, I think it's due (and maybe overdue)

I just noticed that "change rear axel fluid" is actually listed at same mileage frequency as brake / transmission: https://www.chevrolet.com/ownercente...20Corvette.pdf

Does "transmission fluid" mean coolant with antifreeze? Like can it "go bad" just like engine coolant?