U0420: 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 U0420 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

28 complaints filed with NHTSA mention U0420, 28 of them since 2015, across 14 different models. The component owners most often filed it under: steering.

Most-reported models

VehicleComplaintsModel years reported
CHEVROLET COLORADO92015, 2016
JEEP CHEROKEE32015, 2020

Manufacturer service bulletins that name U0420

19 technical service bulletins and manufacturer communications filed with NHTSA mention U0420, from 7 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • JEEP GRAND WAGONEER (2022), bulletin 10231719: Active Lane Management Unavailable Message After Software Flash. U0420-00 Invalid Data Received From Power Steering Set. CADM Inoperative.
  • MAZDA CX-9 (2018, 2019, 2020, 2017), bulletin 10180670: Some vehicles may exhibit that the SBS/SCBS warning light (amber) turns ON right after the engine is started with DTC U0420:68 [FSC] stored in memory. DTC U0420:68 [Forward sensing camera (FSC)]: Error signal received fr…
  • MAZDA MAZDA3 (2017, 2018, 2019, 2020), bulletin 10182100: Some vehicles may exhibit that the SBS/SCBS warning light (amber) turns ON right after the engine is started with DTC U0420:68 [FSC] (Error signal received from electric power steering (EPS) control module) stored in mem…
  • LINCOLN MKC (2019), bulletin 10171929: 2019 MKC - Without Lane Keep Assist AdvanceTrac, Hill Start Assist Message(s) And/Or Stability Control Indicator Lamp Illuminated With DTCs U0420 And U0415 Some 2019 MKC vehicles without lane keep assist may exhibit an a…
  • CHEVROLET COLORADO (2015, 2016), bulletin 10176322: This Preliminary Information communication provides information to the technician that vehicles may have an Antilock Braking System or Malfunction Indicator Lamp illuminated. Also Low Brake Fluid lamp on with the master …
  • GMC CANYON (2015, 2016), bulletin 10176322: This Preliminary Information communication provides information to the technician that vehicles may have an Antilock Braking System or Malfunction Indicator Lamp illuminated. Also Low Brake Fluid lamp on with the master …

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.