When you receive an EICR, any problems found are given a code: C1 means the electrician has found something immediately dangerous — like exposed live wires or a missing earth connection. This needs fixing straight away, and if you're a landlord, the law requires it within 28 days (often sooner). C2 means the fault isn't immediately dangerous but could become so — missing bonding, absent RCD protection, or deteriorated wiring fall into this category. This also needs to be fixed promptly. C3 means the electrician has noted something that doesn't meet current standards but isn't dangerous — it's a recommendation to improve. You're not legally required to fix C3 items, though it's good practice to do so over time. An EICR is Satisfactory only if there are no C1 or C2 items. C3 items alone don't make a report fail.