First, it is critical to clarify what Error 9390 is . It is not a generic OBD-II powertrain code like P20XX. Instead, 9390 is a manufacturer-specific internal code generated by the ESP (Electronic Stability Program) control unit , also known as the ABS control module.
Replaced the differential pressure sensor ($45 aftermarket, $120 OEM) and both rubber hoses. Cleared codes. 9390 did not return. Regeneration now runs normally.
The most frequent culprits for this specific fault code include:
A: Yes, but only to a repair shop. Long-term driving is dangerous. The ESP system (which prevents rollovers) is disabled. In wet or icy conditions, you risk losing control. Additionally, limp mode makes highway merging impossible.