What causes a P1086 code?

P1086 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a P1086 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1086 active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBD-II

P1086

Detects if the pressure in the rail does not rise within a given time period after the running of the engine, a keyoff-keyon or the entrace into

What it means

Fuel Rail Pressure Soft Start Failure. The Engine Control Module (ECM) detected that fuel rail pressure failed to reach the required threshold within a specific timeframe during startup or after a key cycle.