Parts for your 2016 Subaru Forester-Oxygen sensor

2016 Subaru Forester Oxygen Sensor

Yes, the 2016 Subaru Forester uses oxygen sensors, and they’re absolutely relevant to how the engine runs and how cleanly it burns fuel. Technical references confirming fitment include the Subaru Forester 2016 Factory Service Manual (Engine/Emission Control diagnostics), the Subaru parts catalogue for FB25 2.5i and FA20F 2.0XT engines (listing an upstream air–fuel ratio sensor and a downstream oxygen sensor), and OBD‑II regulations mandating upstream and downstream sensors for catalyst monitoring on petrol vehicles. DENSO technical literature similarly identifies the front “A/F” (wideband) sensor and rear (narrowband) O2 sensor arrangement used by Subaru on these engines.

On the 2016 Forester, the upstream air–fuel ratio sensor (often casually called an oxygen sensor) constantly reads the oxygen content of exhaust gas to help the ECU hit that sweet spot of air and fuel. That means smoother running, better economy, and lower emissions. The downstream oxygen sensor sits after the catalytic converter and checks that the cat is doing its job. If it isn’t, or if the sensor is lazy or out of range, it’ll nudge the Check Engine Light and log a code.

There’s no strict service interval in the logbook for O2 sensors, but they’re wear items. Over 160,000–200,000 kilometres, they can slow down or drift, costing fuel and performance. Many workshops recommend proactive replacement of the upstream sensor around that mileage, especially if trims are skewed or response is sluggish on live data. Always use the correct sensor type (wideband A/F up front, narrowband rear) and stick with OEM‑quality parts.

• Common signs it’s time: worse fuel economy, rougher idle, sluggish throttle, fuel smells, or a Check Engine Light with codes like P0131–P0134, P0137–P0138, P0140–P0141, or P0420.
• Good practice at service time: scan for stored and pending codes, review fuel trims, check for exhaust leaks before the sensor, and confirm the cat isn’t tired.

• Replacement tips: work on a cool exhaust, use a proper O2 sensor socket, apply only the pre‑applied thread compound (don’t contaminate the tip), and tighten to the factory torque from the workshop manual. On FA20F turbo models, allow extra access time around heat shields.
• Avoid silicone sprays and leaded additives—they can poison the sensor and converter.

Look after the oxygen sensors and the Forester will reward with tidy fuel use, cleaner emissions, and a nicer drive across Aussie and Kiwi roads.

Popular questions about the 2016 Subaru Forester oxygen sensor

How many oxygen sensors does a 2016 Forester have?
Most AU/NZ‑delivered 2016 Foresters have two: an upstream air–fuel ratio (wideband) sensor before the catalytic converter, and a downstream oxygen (narrowband) sensor after it. Both FB25 2.5i and FA20F 2.0XT variants follow this layout.

Can an oxygen sensor be cleaned instead of replaced?
Not effectively. Contamination and ageing change how the sensing element responds. Cleaning usually doesn’t restore proper function, and sprays can make it worse. If diagnostics show it’s slow or out of range, replacement is the reliable fix.

What’s the usual lifespan of the Forester’s oxygen sensors?
There’s no set schedule, but many last 160,000–200,000 km. If fuel trims are drifting, response is sluggish on a scan tool, or the dash light’s on with O2 or catalyst codes, it’s time to plan a new sensor—especially the upstream one.