Parts for your 2009 Lexus Is-Oxygen sensor

2009 Lexus IS Oxygen Sensor — Purpose, Service and Replacement

Yes, the 2009 Lexus IS uses oxygen sensors. Technical sources including the Lexus/Toyota Repair Manual (TIS) for the 4GR-FSE, 2GR-FSE and 2UR-GSE engines, the Lexus parts catalogue, and DENSO sensor documentation confirm the model runs upstream air–fuel ratio (A/F) sensors and downstream oxygen (O2) sensors to meet OBD‑II and ADR emissions requirements.

On this generation IS, the upstream A/F sensors (one per bank) are wideband units that measure mixture very precisely so the ECU can keep fuelling spot-on in closed loop. The downstream O2 sensors (again, one per bank) sit after the catalytic converters to monitor catalyst efficiency and help flag any emissions faults. Most 2009 IS250/IS350 variants in our market have two A/F sensors and two O2 sensors, the IS F V8 is set up similarly with one pair per bank.

When these sensors are healthy, owners enjoy smooth throttle response, tidy fuel economy and clean tailpipe emissions. When they’re tired, the car can get a bit thirsty, feel doughy off the mark, or light the check engine lamp.

• Common signs the sensors need attention: increased fuel use, rough idle, black soot at the exhaust tip, failed WOF/rego emissions, and fault codes such as P2195/P2197 (stuck lean), P0136/P0138 (rear O2 issues), or heater circuit faults like P0051/P0031.

There’s no strict kilometre-based replacement interval in Lexus schedules, but many technicians in AU/NZ suggest testing sensor performance around 160,000–200,000 km or sooner if fuel trims look skew-whiff. During regular servicing, a quick scan of live data (short/long-term fuel trims, A/F current and voltage, rear O2 switching behaviour) is a smart move. If response is lazy or trims are stretched, replacement pays back in fuel savings and drivability.

• Service tips:
  • Use quality, correct-spec sensors (genuine Lexus/DENSO or equivalent).
  • Work on a warm—not hot—exhaust, and pre-soak threads with penetrant.
  • Avoid twisting the harness, route clips exactly as from factory.
  • Only use anti-seize if specified, many new sensors are pre-coated.
  • After fitting, clear codes and let the ECU relearn trims with a varied drive cycle.

Whether it’s an IS250, IS350 or IS F, keeping the oxygen sensors in good nick helps the 2009 Lexus IS run like it should—quiet, efficient and eager—across Aussie and Kiwi roads.

How many oxygen sensors does a 2009 Lexus IS have?

Most 2009 IS250 and IS350 models use four sensors: two upstream air–fuel ratio sensors (one per bank) and two downstream oxygen sensors (one per bank). The IS F V8 is similarly arranged with one pair per bank. That layout lets the ECU manage fuelling precisely and keep tabs on catalytic converter performance.

When should the oxygen sensors be replaced on a 2009 Lexus IS?

There’s no fixed interval, but checking sensor response around 160,000–200,000 kilometres is wise. Replace earlier if there are drivability issues, poor economy, or fault codes pointing to A/F or O2 sensor performance or heater faults. A scan of live data during servicing will tell the story quickly.

Can a bad oxygen sensor damage the catalytic converters?

Yes, a crook sensor can push fuelling too rich or lean. Running rich for long can overheat and poison the cats, leading to costly repairs. Fixing weak sensors promptly protects the catalysts and restores proper fuel economy and performance.