What causes a P1559 code?

P1559 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 P1559 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1559 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

P1559

Coolant level sensor over range two

What it means

The ECM detects a voltage signal from the coolant level sensor that is higher than the maximum calibrated limit (typically indicating a short to power or a failed sensor).