a couple months ago, I had to replace the thermostat housing on my 08S.
The car ran fine for a couple weeks. Then died while sitting in traffic. Towed home, pulled codes, got p15E8 and P0117. I didn't want to pull the whole housing back off. So I got a another temp sensor from autozone. Cleared the codes. Still the car still will not start. And no codes. Any ideas???
Ps. pulled valve cover, no visible problems with chain. Pulled spark plugs, wet with fuel.

 

Plugs wet with fuel. No spark, start looking there.

 

Found this when searching:
"The general category of P15XX is: Vehicle speed, idle control, auxiliary inputs"
I would check. And then double check. And then triple check all connections on sensors. May be a loose connector came undone or a wire broke and got a bit torn when doing the thermostat and has now come fully undone.

 

update: took everything back apart. checked all sensor connections, wiring harness, vacuum lines,ect. put it back together. no start. but got a code p15E8. "Engine shutdown time :plausibility: time to short relative to temperature drop in engine coolant."
Any ideas??

 

Was this resolved? Having same issue

 

P15E8 0x3392 Engine shutdown time, plausibility: Time too short relative to temperature drop in engine coolant and P0117 Engine Coolant Temperature Circuit Low.

Did you replace the thermostat as well and then get these codes?

 

Only code of p15e8. Car wont start. The car is on its second thermostat housing about 20k miles ago

 

Were you ever able to resolve this issue with P15E8? I too am getting it under the same conditions as you and can't find direction.

 

Did you actually end up fixing your mini ? Thx