Anybody have any idea wtf this might be?

Zoren 370

I agree the non use of ester oil has nothing to do with this.
As someone said your spark plugs might need to be checked or the connectors to the plug is loose.

I drive my car with that service light on. The car still runs great its just annoying to see that light on. But I got used to it.

I just needed to tune the car with all the breather mods I added

EzDz

My z went in limp mode because of a broken maf bolt, the cars are really sensitive. It could be a spark plug going bad or a coil pack

Wonka2581

Cant be the oil, becuse I use RedLine oil in my z... Never had an issue...

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ghotnit

It could also be a bad o2 sensor. I get the P0300 code all the time since I removed my cats and the ECU is freaked out that the readings between the two sensors is not different and thinks it is a “rich” condition and throws the code. So you could get a new o2 sensor or get the free version of Torque and a BT ODBII reader and clear the code when it happens. Perhaps the installer of the exhaust damaged the o2 sensor.

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'14 Nismo AAM 3" TD / AAM Test pipes / AAM CAI / Lowered on Swift / Synolimit Ported TB, upper and lower manifold /DW 1000cc injectors and 340 pump / ECUtek tuned by Hal @ Dynosty / 331whp/268wtq on E85