SantaFe Engine Power Loss

The symptoms you describe, in conjunction with the stored fault code, certainly point toward the aftermarket chip tuning as a potential root cause. Modifications of this nature can sometimes introduce unforeseen conflicts with the factory ECU parameters. To ascertain the precise nature of the fault, could you provide the specific diagnostic trouble code (DTC) that your scan tool reported? This detail may offer further insight into the system at fault.

Thanks for the quick response! The code I pulled was P0299 - Turbocharger/Supercharger Underboost Condition. Does that shed any more light on the situation? Is it possible the tuning messed with the boost control or something similar?

P0299, in the context of aftermarket engine tuning, strongly suggests an issue stemming from altered boost parameters. It is quite plausible that the tuning has either overstressed the turbocharger system or introduced inconsistencies in the boost control mechanisms. Given the complexity of modern engine management systems, reverting to the factory ECU calibration is advisable to verify whether the issue resides within the aftermarket modifications. I recommend having the vehicle inspected by a qualified technician. Continuing to operate the vehicle in its current state could potentially lead to more extensive component damage.

Took your advice and went to a workshop. They confirmed the chip tuning was the culprit. They reflashed the ECU with the stock software, and the problem is gone. Cost me 180€ Thanks for pointing me in the right direction!