2023 Toyota Prius Prime

The vehicle exhibits an unaddressed factory programming defect where the Plug-In Charge Control ECU fails to enter sleep mode while plugged in or resting. This causes continuous, heavy parasitic drain on the 12V auxiliary battery, causing chronic low-voltage state across critical systems. The 12V auxiliary network supplies power to the primary control units, CAN-bus communication modules, and dynamic stability systems. Operating under chronic low-voltage causes system instability, erratic sensor processing, voltage brownouts, and rapid degradation of the 12V battery. In severe traffic or isolated operations, a depleted 12V battery creates a distinct safety hazard, including sudden loss of propulsion control, electrical failure, and stranded conditions. Toyota acknowledged this software logic flaw internally under Technical Service Bulletin T-SB-0054-24. However, because Toyota classifies this defect as a TSB rather than a mandatory safety recall, owners are left vulnerable to unexpected low-voltage electrical failures on public roads and are forced to pay out-of-pocket for an ECU reflash to repair a pre-existing manufacturing defect. This issue requires a mandatory federal safety investigation and zero-cost recall to update all affected control modules.

My 2023 Prius Prime cannot be charged normally in hot weather without triggering a thermal-protection fault on its high-voltage charging system. Avondale Toyota diagnosed it in writing: "CODE P1CE996 CHARGER COOLING FAN REVOLUTION SENSOR COMPONENT INTERNAL FAILURE. THE ELECTRIC CHARGER ASSEMBLY HAS A INTERNAL OPEN CIRCUIT CAUSING IT TO BE INOP. RECOMMEND REPLACEMENT ADD PN# G9090-47061." Quote: $2,516.99 plus ~$200 diagnostic. The vehicle cannot verify its high-voltage charger's cooling fan is operating. In Phoenix heat (100F+), normal charging repeatedly sets the fault and check engine light. I verified by controlled testing: reduced-current charging in cool hours avoids the fault, but any normal charge in heat triggers it — in factory configuration, no obstruction. I am forced to restrict charging to nighttime reduced-current sessions to avoid operating the charger with unverified cooling. A plug-in vehicle that cannot safely complete a normal charge in summer conditions is a safety concern. This is a documented defect: Toyota TSB T-SB-0054-23 (8/7/23), "MIL ON With DTC P1CE996," states the charger assembly "has been modified to reduce the possibility of this condition," superseding part G9090-47060 with G9090-47061 — the part my dealer recommended. The TSB covers VINs before XXX; mine ([XXX]) is in range. Toyota denied coverage at all levels (Case XXX), citing third-owner status and declined unrelated services. A Brand Engagement supervisor acknowledged this identical repair would be fully covered under the PZEV emission warranty if registered in [XXX] — conceding it is a warrantable emissions defect — while denying it for Arizona registration. I request NHTSA review whether a recall or warranty extension is warranted for affected VINs. Hot-climate owners bear full cost of a documented defect on a high-voltage component. No crash, fire, or injury has occurred. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

There is an unexplained loss of 12V power from the 12V battery, and the car will not start. This was reported to the local Toyota dealership on 12/5/25. The car had to be jumped in order to drive it to the dealership/service department. They said the 12V battery was fully charged when they inspected it and there was no parasitic drain on the the battery. They inspected the battery again on 12/30/25 during a routine scheduled service and the 12V battery was good. We have since experienced the inability to start the car on the following dates: 1/10/2026, 2/5/2026, 2/20/2026, 2/22/2026, 2/23/2026. On each of the before mentioned incidents that car had to be jumped by an auxiliary battery pack to get the car to start. We have contact the Toyota dealership again and have a scheduled appointment for 2/25/2026. The dealership had told us that the battery has check out good earlier and they can't replace the 12V battery under the 3 year/36,000 warranty and will need to get Toyota Corporation involved. The car presently has 31,682 miles and it was purchased on 9/19/2023.

The contact owns a 2023 Toyota Prius Prime. The contact stated that upon approaching the vehicle after it had been parked and turned off in the garage, the contact noticed that the hatch door was opened. The contact stated that upon pressing the power button on the hatch and the hatch door power button inside the cabin to close the hatch door, the hatch door failed to close. The manufacturer was notified of the failure and advised the contact to call Roadside Assistance. The contact called Toyota Roadside Assistance who advised the contact to attempt to close the hatch manually. The contact was able to close the hatch door manually. The dealer was not notified of the failure. The vehicle was not diagnosed or repaired. The failure mileage was approximately 7,920. The VIN was not available.

The contact owns a 2023 Toyota Prius Prime. The contact stated while driving 40 MPH with the headlights activated, the low-beam headlights were not providing adequate illumination to light the sides of the roadway properly. The contact stated that shadows were projected to the side of the road from the headlights. The contact had taken the vehicle to a dealer who diagnosed the vehicle and determined that the headlight housing was causing the low beams to be partially shaded. The dealer was informed that when the high beam headlight was activated, the light from the headlight was not casting shadows and the side of the road was lit. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was 9,176.