As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG UNKNOWN SMELL AFTER TAKEOFF. IN FLIGHT DECK AND CABIN. RETURNED TO PDX. REMOVED FROM SERVICE. C/W E175 FIM TASK 21-20-00-810-801-A. RAN A/C FOR 20 MIN WITH NO ADNORMAL SMELLS NOTED. ALSO REF. MCN E210016-3 A/C OK FOR CONTINUED SERVICE. RETURNED TO SERVICE.