A 350z I am looking at buying has a Mishimoto Radiator/hoses/fan shroud/and Thermostat. The CEL comes on occasionally and he says the ECU (Stock) is noticing the engine temp is cooler than normal and is triggering the CEL. I plan on having a scanner read for codes before I buy this, but is this possible? Seems like he is trying to cover something up to me. Claims an Osiris tune can make it go away.

Thanks for any information!

 

Yea, its from the mishimoto thermostat cuz it takes the motor longer to warm-up unless u go FI, but if you gonna be using it for DD OEM thermostat would fix this. The code would be p0128??? Not sure??

Any more info would be nice??

 

With uprev you can disable CEL error p0117 and p0118, about low or high coolant temperature input.
I don't know if it's your case...

 

easy way to check is to just swap in the stock thermostat and see if it still throws the code

 

+1 on OEM Thermostat

 

cars with no thermostat dont throw codes. very odd he is getting one.

what is the exact code #?

 

I was getting CEL from the Mishimoto T-Stat also
The code it would give me is coolant not up to temp I forgot the exact code.
I put back the OEM T-Stat no problem.

I guess between the Koyo R-Core and the Mishimoto T-Stat the coolant would run too cool

 

its emissions related, a colder engine will use more fuel. the mishimoto thermostat is probably a lower temp than stock. that is why you are getting a check engine light.

 

Yes that is the code I get with the Mishimoto thermostat. I just erase codes after with a basic diagnosis tool. It usually stays gone for a while, maybe with the uprev you can turn off that DTC. It stays cooler with that thermostat on DD
and if you race too. Dont know if it makes any difference.

 

Also the larger volume in the aftermarket radiator would increase the time to warm an engine (longer time to warm extra coolant).

I think it's time based. Like the o2 sensors if the ecu doesn't get a heat reading it needs in a set amount of time it throws a code. If it's cold outside it could happen more often. This is common in cold climates with older o2 sensors. Takes them too long to warm up. Same concept with a better cooling system on a car. Not sure why some cars are more sensitive to throwing that code over others though.

 

Sorry to bump a 5 month old thread but Id rather go from here than make a new one.


Im getting the same CEL but the car doesnt have an aftermarket T stat. If I delete the code it comes back 150-200 miles later. Do I replace the T stat with another OE spec one?

 

Thermostat is probably stuck open, replace it. I get the code on my car when it is cold out , my thermostat is stuck open (set it up that way) and actually block off half my radiator now when the temp is less than 40 and the car is not on the track.

 

Yes I had this problem with the mishimoto T stat. The code comes on you can erase it with a scanner but after a little while it will come back. It does keep the water temp colder so I wanted to keep it. I happen to have the osiris tuner
and turned off the dtc on that. It worked for a while then it still came back on.
Ok the way to do it turn off dtc and get a reflash then it stayed off, possibly
tune something else also so you dont reflash just for that.