P203B: 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 P203B 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

6 complaints filed with NHTSA mention P203B, 6 of them since 2015, across 3 different models. The component owners most often filed it under: engine.

Most-reported models

VehicleComplaintsModel years reported
VOLKSWAGEN PASSAT42012, 2013

Manufacturer service bulletins that name P203B

37 technical service bulletins and manufacturer communications filed with NHTSA mention P203B, from 7 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • FORD F-750 SD (2024, 2025), bulletin 11006773: Some 2024-2025 F-650/F-750 vehicles built on or before 22-Jul-2024 and equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P206B, and/or P220…
  • FORD F-250 SD (2023, 2024), bulletin 10250850: Some 2023-2024 F-Super Duty vehicles equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) U02A2, P206B, P203B, P208A, P20FA, P20FD, and/or P20FC stor…
  • FORD F-650 SD (2023, 2024), bulletin 11006774: Some 2023-2024 F-Super Duty vehicles built on or before 22-Jul-2024 and equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P206B, and/or P22…
  • FORD F-350 SD (2023), bulletin 10241617: Some 2023 F-Super Duty vehicles equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) U02A2, P206B, P203B, P208A, P20FA, P20FD, and/or P20FC stored in…
  • FORD F-150 (2018, 2019, 2020, 2021), bulletin 10212102: Some 2018-2021 F-150 vehicles equipped with a 3.0L diesel engine, 2016-2022 F-650/F-750 vehicles equipped with a 6.7L engine, and 2017-2022 F-Super Duty vehicles equipped with a 6.7L engine and built on or before 08-Mar-…
  • FORD F-550 SD (2020, 2021), bulletin 10189774: This article supersedes TSB 20-2336 to update the Title, Issue, Action, vehicles affected and production fix date. Some 2020-2021 F-Super Duty vehicles equipped with a 6.7L engine built on or before 10-Feb-2021 may exhib…

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.