{"nhtsa_id":11027729,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-01-21","date":"2026-01-14","document_id":"18-001-26","mfr_campaign":null,"replaces":null,"component":"POWER TRAIN","mfr_system":null,"summary":"Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0420 - Catalyst System Efficiency Below Threshold Bank 1. ● P0430 - Catalyst System Efficiency Below Threshold Bank 2. Customers may also experience the following: ● Catalyst damage and restricted exhaust flow, resulting in a reduction of engine power. This bulletin involves reprogramming the PCM with the latest available software.","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11027729-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11027729-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11027729","components":[{"id":"powertrain","name":"Transmission and driveline","parent":null}],"codes":["P0420","P0430"],"topics":[],"vehicles":[{"make":"JEEP","model":"GRAND CHEROKEE","year_from":2018,"year_to":2018,"match":"exact","vehicle_ids":["2018_jeep_grand-cherokee"]}],"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":[]}