How do I troubleshoot an Ariston boiler displaying error 101?

Troubleshooting involves several steps. First, check the water pressure to ensure it's within the acceptable range for your boiler. Next, inspect the pipes for any blockages or kinks. If those are clear, the flow sensor might be faulty. A qualified technician can test and replace the sensor if necessary. Don't attempt repairs if you're not comfortable working with plumbing and electrical systems.