What causes a U3079 code?

U3079 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 U3079 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U3079 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

U3079

Manufacturer-specific network code U3079

What it means

Invalid data received from the cabin climate temperature sensor or humidity sensor. The AC system cannot determine how to adjust blower speed.