What causes a P1115 code?

P1115 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 P1115 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1115 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

P1115

Coolant temp high warning level

What it means

P1115 indicates that the engine coolant temperature has exceeded the maximum safe operating threshold (typically above 212°F-220°F depending on engine model), triggering a warning to prevent engine damage.