Bosch furnace error 603

error 603 is the most common error code for a furnace; the furnace will not work at all and will shut down.

Sending an email to the customer and following up with a call to offer them an opportunity to get in touch with a service technician and diagnose the issue.

This article provides an overview of the error code 603 means and how the error code can be fixed.

A Bosch furnace may give an Error Code 603 (or I/M Troubleshooting Code P10-11) when a user adds a new furnace or replaces parts in an older furnace. The most common cause for this type of error is when the wrong thermostat or wiring is being used.

Today, there are a lot of guidelines given to assemble your furnace. As time goes by, these guidelines continue to change.

The bosch furnace error 603 is one specific error you’ve probably never encountered before. But that doesn’t mean that it doesn’t exist.

The bosch furnace error 603 means that one of the valves in the boiler has been blocked and needs to be replaced. If you go ahead and replace this valve, then your heating system will work again.