An EICR is an inspection and test of an electrical installation to see if it is satisfactory for continued use. Codes are given for any areas of non-compliance with current wiring regulations (BS7671).
C1 code is defined as "Danger present risk of injury. immediate remedial action required"
C2 code is defined as "Potentially dangerous - Urgent remedial action required"
C3 code is defined as "Improvement recommended"
FI code is defined as "Further investigation required without delay"
This information can be found in Appendix 6 of BS7671.
Wiring regulations do not specify how quickly any remedial work should be undertaken, but if there are genuine C1 observations, it can be poor judgement not to address them, as electricity can kill a healthy person very quickly if exposed live parts are touched. Which is generally what C1's relate to, (immediate danger). However, there is also a tendency for some less competent persons undertaking the inspection to incorrectly code some observations. If the electrical installation is genuinely that dangerous, you may well find it cheaper addressing the problems ASAP, rather than the costs of picking up the pieces following damage due an electrical fire, or serious shock injury to a family member.
Doc H.