Ford AE8Z9G444B Oxygen Sensor Assembly

The AE8Z9G444B is a heated zirconia dioxide oxygen sensor designed for downstream (post-catalyst) monitoring on 2011-2019 Ford Fiesta models equipped with 1.6L four-cylinder engines. It features a four-wire configuration with an integrated heater circuit for rapid closed-loop operation, providing a 0-1V signal output proportional to exhaust oxygen concentration. The sensor mounts in the rear lower exhaust position with an M18x1.5 thread interface. Constructed with a stainless steel housing and ceramic sensing element, the unit meets Ford OEM durability standards for thermal cycling and contamination resistance. Direct replacement for Ford part numbers AE8Z-9G444-B, AE8Z9G444C, and base number 9G444. Cross-references include Denso 234-4555, NGK/NTK 22138 (OZA658-D3), Motorcraft DY-1152/DY-1158, and aftermarket numbers AE81-9G444-BC, 1743702.