{"nhtsa_id":11025769,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2025-12-01","date":"2025-11-11","document_id":"SC352_TSB","mfr_campaign":"SC352","replaces":null,"component":"ELECTRICAL SYSTEM","mfr_system":null,"summary":"VOLUNTARY SERVICE CAMPAIGN: HVAC SOFTWARE UPGRADE FOR PTC OPERATION LOGIC IMPROVEMENT (SC352) - This bulletin provides information to upgrade the Heating, Ventilation, and Air Conditioning (HVAC) control software on certain 2025-2026MY Carnival HEV (KA4 HEV) vehicles produced from May 16, 2024 through September 8, 2025, to prevent excessive discharging of the 12V battery by the Positive Temperature Coefficient (PTC) heater under certain operating conditions. When the engine is below operating temperature, the PTC heater is used to provide additional heat to the cabin. In very cold environments and under high electrical load, the PTC heater in the subject vehicles may discharge the 12V battery faster than it can charge. If the 12V battery becomes excessively discharged, the vehicle may enter Limp Home Mode with speed temporarily limited to a maximum of 31mph until the vehicle reaches normal operating temperature. There are no warning lamps or warning messages associated with this condition.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2025/MC-11025769-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2025/MC-11025769-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11025769","components":[{"id":"electrical","name":"Electrical system","parent":null}],"codes":[],"topics":[],"vehicles":[{"make":"KIA","model":"CARNIVAL HYBRID","year_from":2025,"year_to":2026,"match":"base","vehicle_ids":["2025_kia_carnival","2026_kia_carnival"]}],"as_of":"2026-10-19","note":"A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.","attribution":[]}