P0691: 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 P0691 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

1 complaints filed with NHTSA mention P0691, 1 of them since 2015, across 1 different models. The component owners most often filed it under: electrical system.

Manufacturer service bulletins that name P0691

5 technical service bulletins and manufacturer communications filed with NHTSA mention P0691, from 3 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • FORD F-650 SD (2016, 2017, 2018, 2019), bulletin 10160939: Some 2016-2019 F-Super Duty and 2016-2019 F650-750 vehicles equipped with 6.7L engine may exhibit a concern where the engine cooling fan stays on at all times or is inoperative. Diagnostic trouble codes (DTCs) P0480, P04…
  • CHEVROLET CAMARO (2016), bulletin 10095558: THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN WITH THE STEP TO DIAGNOSE AND REPAIR VEHICLE THAT MAY HAVE AN ENGINE COOLING FAN THAT IS INOPERATIVE WITH DIAGNOSTIC TROUBLE CODE P0480 OF…
  • CADILLAC ATS (2013), bulletin 10112459: This Preliminary Information communication provides information to the technician about vehicles that have an engine overheat concern or cooling fans are inoperative. Technician may find Diagnostic Trouble Codes P0480, P…

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.