Parts for your 2015 Subaru Exiga-Oxygen sensor

2015 Subaru Exiga oxygen sensor — what it does and when to replace it

Technical references confirm the 2015 Subaru Exiga is fitted with oxygen-sensing hardware. The Subaru Factory Service Manual for the YA-series Exiga (Fuel and Emission Control section) specifies an upstream air/fuel ratio sensor and a downstream heated oxygen sensor. Subaru’s FAST electronic parts catalogue lists these sensors for both the FB25 and EJ20 petrol engines used around this model year. Regulatory context backs this up too: ADR 79/02 (Euro 4-equivalent) and OBD-II requirements applicable in Australia and New Zealand necessitate oxygen sensors on late-model petrol vehicles to manage emissions and monitor the catalytic converter.

On a 2015 Exiga, the oxygen-sensor system includes a wideband air/fuel (A/F) sensor before the catalytic converter and a conventional heated O2 sensor after it. The front sensor constantly reports how rich or lean the burn is so the ECU can trim fuel right on the money for smooth running, good power and tidy emissions. The rear sensor keeps tabs on the catalytic converter’s efficiency and will throw a code if it’s not doing its job.

While not a typical “every-service” item, oxygen sensors are wear components. By about 160,000–200,000 km, response can slow or readings can skew, nudging fuel use up and making the Exiga feel a bit lazy or uneven at idle. Common symptoms and fault codes include higher petrol consumption, a Check Engine Light, rough cold starts, and OBD-II codes such as P0134/P0137 (sensor circuit), P0171/P0172 (fuel trim), or P0420 (catalyst efficiency).

Good servicing practice on a 2015 Exiga oxygen sensor includes: visually checking the sensor bodies and wiring for heat damage or rubbed insulation, ensuring there are no exhaust leaks ahead of the sensors, and avoiding silicone sealants or leaded additives that contaminate the sensing element. When replacement’s due, using quality OEM-equivalent sensors (often Denso on Subaru) helps avoid drivability dramas. Apply only sensor-safe anti-seize if the new sensor doesn’t come pre-coated, route the harness exactly like the original, and tighten to the Subaru torque spec (many Subaru sensors fall in the 35–44 N·m range—always verify for the exact engine). After fitting, clear codes, reset fuel trims and perform a proper drive cycle so the ECU relearns quickly.

Driven with a dud sensor, the car will generally still run, but it’ll likely drink more fuel and can stress the catalytic converter. Sorting it early keeps the Exiga running sweet and compliant for WOF/roadworthy checks.

Popular questions

How many oxygen sensors does a 2015 Subaru Exiga have?
Most 2015 Exiga petrol models run two: a front wideband A/F sensor before the cat and a rear heated O2 sensor after it. Variations by engine or market are possible, but two is typical.

When should the oxygen sensor be replaced on a 2015 Exiga?
There’s no fixed interval, but many are replaced around 160,000–200,000 km or when faults appear. If fuel economy drops, the CEL comes on with O2-related codes, or a WOF/roadworthy emissions check is shaky, testing and likely replacement is smart.

Is it safe to keep driving with a faulty oxygen sensor?
Usually the car will limp along, but expect higher fuel use and a risk of catalyst damage if it runs too rich. It’s best to diagnose promptly and replace the sensor to protect the converter and keep running costs down.