P0688: 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 P0688 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 P0688, 1 of them since 2015, across 3 different models. The component owners most often filed it under: engine and engine cooling.

Most-reported models

VehicleComplaintsModel years reported
JEEP GRAND CHEROKEE42007, 2008

Manufacturer service bulletins that name P0688

4 technical service bulletins and manufacturer communications filed with NHTSA mention P0688, from 2 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • RAM 1500 (2019, 2020, 2021, 2022), bulletin 10231724: Crank, No Start Condition, Diagnostic Trouble Code (DTC) P0688 - Auto Shutdown Relay Sense Circuit
  • CHRYSLER CHRYSLER, bulletin 10159987: Part Description: TIPM [Totally integrated power module] Issue Description: Before replacing a Totally Integrated Power Module (TIPM) for no start condition. Specifically when P0688 or P0685 fault code is active please c…

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.