Viking Range Error Code Comm

The Comm error on a Viking range means the RS485 serial communication link between the Electronic Oven Control board (EOC4) and the User Interface board has been lost or cannot be established. This prevents the two boards from exchanging the data needed for the range to function. The error must be resolved before normal oven operation can resume.

Start by powering down the unit at the circuit breaker and waiting a few minutes before restoring power. If the error persists, inspect the wiring harness connecting the EOC4 and UI board for loose connections, damaged wires, or corroded terminals. If the harness is intact and connections are secure, one of the two control boards is likely at fault and will need to be tested and replaced.

Repair costs depend on which component has failed. If only the wiring harness needs replacement, costs are generally lower, typically in the range of $50 to $150 for parts and labor. Replacing a UI board or EOC4 control board on a Viking range can cost between $200 and $600 or more depending on the specific model and labor rates in your area. Getting a diagnostic inspection first helps avoid replacing parts unnecessarily.

A power reset is the recommended first step and may clear the Comm error if it was caused by a temporary signal disruption or software glitch. Turn the range off and cut power at the circuit breaker for several minutes before restoring power. If the error returns after the reset, there is likely a hardware problem with the wiring harness or one of the control boards that requires further diagnosis.

A Comm error means the control system cannot function properly, so the range should not be relied upon for normal cooking until the issue is resolved. The error itself does not indicate a gas leak or fire hazard, but operating an appliance with a faulty control communication link is not recommended. Power the unit down until the fault is diagnosed and corrected.