U0404: owner reports and bulletins

Network / communication. We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got U0404 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.

What owners report to NHTSA

16 complaints filed with NHTSA mention U0404, 5 of them since 2015, across 5 different models. The component owners most often filed it under: power train.

Most-reported models

VehicleComplaintsModel years reported
JEEP GRAND CHEROKEE92005, 2007
JEEP COMMANDER32006, 2007

Manufacturer service bulletins that name U0404

11 technical service bulletins and manufacturer communications filed with NHTSA mention U0404, from 4 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • LAND ROVER RANGE ROVER SPORT (2017, 2018), bulletin 10130739: A customer may be unable to select a transmission gear and/or start the engine. A 'Gearbox fault' message may also be displayed on the Instrument Cluster (IC). Switching the ignition 'OFF' and then 'ON' clears the fault.…
  • JEEP GRAND CHEROKEE (2016), bulletin 10121646: Flash: Transmission Diagnostic And Shift Enhancements This bulletin involves reprogramming the Transmission Control Module (TCM) with the latest available software. Some customers may experience a Malfunction Indicator L…
  • DODGE DURANGO (2016), bulletin 10121646: Flash: Transmission Diagnostic And Shift Enhancements This bulletin involves reprogramming the Transmission Control Module (TCM) with the latest available software. Some customers may experience a Malfunction Indicator L…
  • JAGUAR F-TYPE (2014), bulletin 10064337: "SITUATION: THE TRANSMISSION MAY BE STUCK IN PARK (P) ON ENGINE START UP. CAUSE: THIS MAY BE CAUSED WHEN, UNDER CERTAIN CONDITIONS, AN ENGINE START OCCURS BEFORE THE TRANSMISSION CONTROL MODULE (TCM) AND TRANSMISSION CON…

Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.