From your test data, combine HS Driver change, we can see that:Before HS Driver change, with the improper 17K Pump (which used all the time from 2014 to 2019), as the OL Id is low, so even if the load not match with ECM, it will not trig FC4291 as the Voltage under the trigger voltage 1.4V.After HS Driver change, with the improper 17K Pump, as the OL Id has some level increase, so the diagnostic voltage also increased, and go into 1.4V-1.6V range. Which makes FC4291 occur.Before HS Driver change and After HS Driver change, with the Proper Pump load