P0431: owner reports and bulletins

Powertrain (generic, all makes). We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got P0431 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

3 complaints filed with NHTSA mention P0431, 2 of them since 2015, across 3 different models. The component owners most often filed it under: engine and engine cooling.

Manufacturer service bulletins that name P0431

1 technical service bulletins and manufacturer communications filed with NHTSA mention P0431, from 1 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • MITSUBISHI ECLIPSE (2006, 2007, 2008), bulletin 10173901: Due to variations in production, certain exhaust manifold mounted catalytic converters may experience catalyst layer separation on affected vehicles. If this occurs, the MIL will illuminate with DTC P0421 or P0431, "Warm…

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.