Typical maybe and since he is aware of it he surely has calculated the risk and charged for it with every repair. AND has calmly ordered a replacement.
Since you haven't mentioned what kind of car it is it is hard to say what might be related. My answer when asked whether things are related is to state that no senario can be hypothesized if one doesn't know what is wrong. Working on the dash sure won't cause a check engine light for EGR, but on some systems a speed signal shorted to ground could cause a check engine light
Bosch Master, ASE Master, L1
33 years MB technician