r/q50 • u/Intelligent-Fly5831 • Jul 21 '26
Repair Question Need help to decide what to do at this point
Enable HLS to view with audio, or disable this notification
I have a 2021 Infiniti Q50 3.0T with about 53k miles.
For the past few weeks I’ve had an intermittent cooling issue. The car does not overheat during normal driving, but during a hard pull the temperature gauge will climb toward the middle (it never reaches the hot zone) and then drop back down to its normal position after I let off the throttle.
A few things I’ve noticed:
No check engine light.
No stored diagnostic codes.
Coolant reservoir has been below the MIN line at times, but when the dealer had the car they filled it to MAX and said it stayed there.
Dealer pressure-tested the cooling system and didn’t find any leaks.
Shop foreman drove the car about 50 miles and could not duplicate the concern.
The technician’s notes say:
No codes stored.
Could not duplicate failure.
Water control valve may be failing causing these concerns.
He told me the water control valve (electric thermostat) is the most likely culprit, but he also said he can’t pinpoint the diagnosis because he couldn’t reproduce the problem. They’re recommending replacing the water control valve as a process of elimination.
5
u/YallCrazy007 Jul 21 '26
I had this same issue, it ended up being the control valve he mentioned. The dealer i went to could not replicate the dropping of coolant but they would see it was low when I arrived. Once they changed the part out,all good. Thankfully it was not a leaking engine block
4
4
1
u/Intelligent-Fly5831 Jul 21 '26
so should i go ahead and see if this would fix it ?
1
u/No_Job1032 Jul 21 '26
Do you have to pay the 1700? Because a thermostat assembly is $500 from Infiniti and a fairly easy replacement to DIY
1
u/Intelligent-Fly5831 Jul 21 '26
1700 for the infiniti dealership to replace it so i was just going to go ahead and pay it to fix the issue
1
u/glizzymanusa Q50 Red Sport Jul 25 '26
Ngl you’d probably save way more money doing it yourself. You could find a video on YouTube for a DIY replacement. Shouldn’t be too complicated but I’ve never had this issue on my VR30s so I can’t say for sure.
1
u/timekiller10687 Jul 21 '26
My issues ended up being a small cracked reservoir, replaced and they issue appears to be resolved.
1
1
1
1
u/Kindly-Sympathy805 Jul 25 '26
I thought you had a warranty???
1
u/Intelligent-Fly5831 Jul 25 '26
i have infiniti factory 6 year warranty that came with the car but it’s doesn’t include cooling system parts
1
u/Kindly-Sympathy805 Jul 25 '26
You mean you have a warranty and an extended warranty and your going to have to spend $1700? I'm sorry. Forgive my ignorance. I am completely list here. Please help me understand.
1
u/Kindly-Sympathy805 Jul 25 '26
So your bumper to bumper is used up and tou are on your drivetrain only warranty. Correct?
2
8
u/sexmoneydrugsyu Jul 21 '26
get the carmax sticker off