What causes a P0649 code?

P0649 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 P0649 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0649 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.

OBDIY

OBD-II

P0649

Speed Control Indicator Lamp Control Circuit Malfunction

What it means

The Engine Control Module (ECM) has detected an open, short, or ground issue within the wiring circuit dedicated to operating the cruise control/speed control indicator lamp.