2007 Camry V6 P0352 Check Engine Light Not Resetting After Ignition Coil Replacement

I have a 2007 Toyota Camry LXT with a V6 engine. The check engine light came on and the diagnostic code is P0352, indicating an ignition coil circuit fault. I had all six ignition coils replaced, but the check engine light remains on after three days. My mechanic suggested that if the code doesn't reset, we may need to replace the ECM (Engine Control Module). My question: Does the vehicle require a specific number of drive cycles or miles before the P0352 code resets? I've tried various methods online, such as disconnecting the battery for several hours or using a cheap OBD-II scanner to clear the stored codes. However, I'm unsure if these methods are valid or will actually resolve the issue. The car doesn't appear to be misfiring noticeably, but fuel efficiency has dropped by about 1 mile per gallon. Since I live in California and need to pass smog inspection soon to transfer ownership (the car was given to me by my niece), this is a major concern. I'm looking for reliable advice on whether clearing the code via OBD-II tools or battery disconnection will work, and if there are any other diagnostic steps I should take before considering an ECM replacement. Any insights would be greatly appreciated.