Parts for your 2018 Lexus Is-Oxygen sensor

2018 Lexus IS oxygen sensor: purpose, care, and when to replace

Technical sources confirm the 2018 Lexus IS uses oxygen-sensing hardware. The Lexus factory repair manual (TIS) for the 8AR‑FTS (IS300) and 2GR‑FKS (IS350) details an upstream wideband Air‑Fuel Ratio (A/F) sensor and a downstream Heated Oxygen Sensor (HO2S) as part of the SFI engine control. The Lexus Electronic Parts Catalogue lists these sensors for 2018 IS variants, and the vehicle’s OBD‑II diagnostics include relevant DTCs (e.g., P0136, P0138, P015A), all of which rely on these sensors being fitted.

On a 2018 Lexus IS, the oxygen-sensor setup is there to keep the engine running clean and efficient. The upstream wideband A/F sensor constantly measures the oxygen content in the exhaust, letting the ECU fine‑tune fuel trims for crisp throttle response, smooth idle, and top fuel economy. The downstream HO2S keeps tabs on catalytic converter performance, making sure emissions stay within spec and warning the driver if the cat isn’t doing its job.

How many are fitted? The 4‑cyl turbo IS300 (8AR‑FTS) typically runs one upstream A/F sensor and one downstream O2 sensor on its single bank. The V6 IS350 (2GR‑FKS) uses two banks, so expect two upstream A/F sensors and two downstream O2 sensors.

They’re not a scheduled service item, but they do wear out. Age, heat, contaminated fuel, oil or coolant consumption, and exhaust leaks can shorten their life. Many owners see reliable operation well past 160,000 km, but gradual degradation can creep in earlier.

Common clues it’s time to act include:

• Check Engine lamp with O2/A/F‑sensor or fuel‑trim codes
• Higher fuel use, lazier performance, or a rich exhaust smell
• Rough idle or hesitation, and failed emissions tests

Good servicing habits help. During routine maintenance, a technician should visually check sensor wiring and connectors, look for exhaust leaks ahead of the upstream sensor, and confirm there’s no oil or coolant contamination that could foul the sensing element. If replacement’s needed, go for OE‑quality parts (the factory sensors are wideband and calibrated for the Lexus ECU). Sensors usually come pre‑coated on the threads—avoid extra anti‑seize and never touch or contaminate the tip. Correct torque and careful harness routing are important, especially near turbo heat on the IS300.

After fitting, clear codes and complete a proper drive cycle so the ECU can relearn trims and set readiness. Driving on a crook sensor can hammer fuel economy and, worse, cook the catalytic converter—so it’s worth sorting promptly.

Popular questions

How many oxygen sensors are on a 2018 Lexus IS?
IS300 (8AR‑FTS) generally has two: one upstream A/F sensor and one downstream O2 sensor. IS350 (2GR‑FKS) typically has four: an upstream and downstream sensor on each bank. The exact count can be confirmed against the VIN and the Lexus EPC.

When should the oxygen sensors be replaced?
They’re replaced when faulty rather than by a strict interval. Many last beyond 160,000 km, but if there are O2/A/F‑sensor codes, rising fuel use, or driveability issues, test and replace as required. Always fix exhaust leaks and any contamination issues at the same time.

Can an oxygen sensor be cleaned instead of replaced?
No. Cleaning usually damages the sensing element and won’t restore proper response. If diagnostics confirm a slow or biased sensor, replacement is the reliable fix.