Hardware Test Error 4SNS/1/40000001:ICOC--124

Symptoms: MacBook Air (2012) won't keep charge and takes extended time (several hours) to charge even to 40%. Used activity monitor to check processes and nothing unusual. Checked battery via Battery menu (Option key) and it says "normal." We would love to keep this computer usable for a little longer...any suggestions would be appreciated. FYI: we live more than 4 hours from the closest Apple store so "genius bar" appointments aren't possible. Did the shorter Hardware Test and received alert: 4SNS/1/40000001:ICOC--124.