Parts for your 2017 Subaru Impreza-Oxygen sensor

2017 Subaru Impreza Oxygen Sensor (A/F and O2 Sensors)

Yes, the 2017 Subaru Impreza is fitted with oxygen-sensing hardware. Technical sources including the Subaru Factory Service Manual for 2017MY Impreza (Engine Diagnostics), Subaru parts catalogues, and emissions requirements (e.g., ADR 79/04 Euro 5/OBD-II) confirm it uses a front air–fuel ratio (A/F, wideband) sensor and a rear oxygen (O2, narrowband) sensor. These sensors are standard for closed-loop fuel control and catalytic converter monitoring on this model’s FB20 engine.

On the 2017 Impreza, the front A/F sensor sits upstream in the exhaust manifold and constantly measures oxygen content so the ECU can trim fuelling with fine precision. That keeps the air–fuel mix on point for smooth running, good fuel economy, and low emissions. The rear O2 sensor sits after the catalytic converter to check how well the cat is cleaning up the exhaust, if the readings don’t look right, it flags a fault to protect the cat and the wallet.

There’s no fixed replacement interval in Subaru schedules for these sensors, but age, heat, and fuel quality can slow them down. If the Impreza starts drinking more fuel than usual, idles a bit rough, or throws a check-engine light with codes like P0131/P0134 (front A/F) or P0137/P0420 (rear O2/cat efficiency), the sensors deserve a look. Many workshops recommend testing or replacing around the 160,000–200,000 km mark if symptoms are showing.

Good servicing habits help the sensors live longer. Keep on top of air filter changes, fix any exhaust leaks pronto, and use quality petrol (E10 is fine if the car is approved). When replacement is needed, genuine or high-quality OEM-equivalent sensors keep the ECU happy and the trims stable.

DIY-minded owners can swap sensors at home, but a few tips go a long way:

• Work on a stone-cold exhaust, spray penetrant on the threads, and use an O2 sensor socket.
• Don’t twist the harness, route it exactly like the original and clip it away from heat.
• Many new sensors have coated threads—only use a tiny dab of high-temp anti-seize if specified by the manufacturer, and tighten to the factory torque spec.
• Clear codes and fuel trims with a scan tool after fitting, then road-test.

Look after the oxygen sensors and the 2017 Subaru Impreza will run sweet as—better economy, cleaner tailpipe, and a happier cat come WOF/rego time.

Popular questions

How many oxygen sensors does a 2017 Subaru Impreza have?
It uses two: a front air–fuel ratio (A/F, wideband) sensor before the catalytic converter and a rear oxygen (O2) sensor after the converter. The front handles fuel control, the rear checks catalyst efficiency.

What are common symptoms of a failing oxygen sensor on this model?
Expect higher fuel use, rough or hesitant running, a check-engine light, and sometimes a sulphur smell from the exhaust. Scan tools may show codes like P0131, P0134, P0137, or P0420.

When should they be replaced, and is it safe to keep driving?
Replace when faults are confirmed by testing or persistent DTCs, or proactively if performance drops after high kilometres. Short drives are usually safe, but extended driving with a failed sensor can damage the catalytic converter and cost more in fuel.