C1604: owner reports and bulletins

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

Got C1604 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

7 complaints filed with NHTSA mention C1604, 6 of them since 2015, across 4 different models. The component owners most often filed it under: electrical system.

Most-reported models

VehicleComplaintsModel years reported
HYUNDAI ELANTRA42009, 2010, 2020

Manufacturer service bulletins that name C1604

1 technical service bulletins and manufacturer communications filed with NHTSA mention C1604, from 1 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • KIA SELTOS (2021), bulletin 10173450: TECHNICAL SERVICE BULLETIN: SERVICE ACTION: FRONT RADAR DTC JUDGEMENT LOGIC IMPROVEMENT (SA414) - This bulletin provides the procedure to improve the logic of the front radar software on some 2021MY Seltos SX (SP2) vehic…

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.