1588A025 Upstream Oxygen Sensor，Exhaust Front Lambda O2 Sensor

Thread‑mounted on exhaust manifold before catalytic converter, this zirconia‑type upstream lambda sensor is core signal component of fuel injection system. It samples exhaust gas oxygen concentration, feeds signal back to engine ECU, ECU adjusts fuel injection pulse width to maintain ideal air‑fuel ratio. Engine starting performance, idle smoothness, acceleration response and fuel economy are directly affected by this sensor.

Long‑term high‑temperature exhaust impact, carbon soot accumulation and internal element aging cause signal drift. Typical failure symptoms: check‑engine warning lamp illumination, unstable idle shaking, increased fuel consumption, black exhaust smoke, weak acceleration power and related OBD fault codes. Many technicians repeatedly inspect fuel pump and injectors, ignoring defective upstream oxygen sensor as real fault source.This replacement oxygen sensor replicates OEM thread dimension, signal output parameter and complete sealing gasket. High‑temperature resistant sensing probe withstands harsh exhaust manifold environment. Remember to apply anti‑seize compound to threads before installation. Suitable for Mitsubishi 4G69 engine fuel‑injection‑system overhaul assignments.