Parts for your 2007 Ford Focus-Oxygen sensor

2007 Ford Focus Oxygen Sensor: what it does and when to replace it

Yes, the 2007 Ford Focus is fitted with oxygen sensors. This is supported by Ford’s Workshop Manual for the 2005–2007 Focus (Section 303-14A, Fuel and Emissions), which identifies heated oxygen sensors (HO2S) located before and after the catalytic converter on petrol models, and by the 2007 Focus wiring diagrams that show the HO2S circuits. The Motorcraft service parts catalogue also lists upstream and downstream oxygen sensors for this model year. Additionally, OBD‑II/ADR 79 emissions requirements in Australia and New Zealand necessitate oxygen sensors for closed-loop fuel control and catalyst monitoring.

On a 2007 Focus, the oxygen sensor measures how much oxygen is left in the exhaust, letting the engine control unit trim fuel on the fly. The upstream sensor (before the cat) keeps mixtures right on the money for smooth running, good fuel economy, and low emissions. The downstream sensor (after the cat) keeps an eye on catalytic converter efficiency. If either drifts out of spec, the car can chew through more fuel, feel a bit doughy off the line, or light up the check engine lamp.

Oxygen sensors are wear items. By around 160,000 kilometres, many start responding slower or reading inaccurately. That doesn’t always throw a fault right away, but it can still cost money at the bowser. If the Focus shows a CEL with codes like P0130–P0161, uses more fuel than usual, idles roughly, or has a whiff of sulphur from the exhaust, the sensors deserve a look.

There’s no real “servicing” of the sensor element itself, but good habits help it live longer: fix exhaust leaks, avoid silicone-heavy sealants that can contaminate the sensing tip, keep oil consumption in check, and make sure the engine’s air filter and spark plugs are in order. When replacement time comes, go for quality parts (Motorcraft, Bosch, or NTK suit the Focus well).

DIY-minded drivers can tackle the job with a sensor socket and a cool exhaust. Unplug the connector, crack the old sensor, and wind in the new one (most quality sensors arrive with anti‑seize on the threads). Tighten to the Ford spec, route the harness clear of heat, clear any codes, and complete a short drive cycle so the ECU relearns trims.

• Typical count: petrol Focus models = 2 sensors (pre‑ and post‑cat), XR5 Turbo also uses two. Many TDCi variants use at least one lambda sensor.
• Check sooner if fuel use spikes, the CEL appears, or the car fails an emissions test.

How many oxygen sensors does a 2007 Ford Focus have?
Most petrol 2007 Focus models in Australia and New Zealand have two: one before the catalytic converter and one after it. The XR5 Turbo also uses two. Diesel TDCi variants typically run at least one lambda sensor, and some have a second for catalyst monitoring.

When should the oxygen sensor be replaced?
Many owners consider replacement around 160,000 kilometres, or sooner if there are fault codes (P0130–P0161), rough running, or rising fuel consumption. A scan showing a lazy sensor response is another cue to replace.

Can a bad oxygen sensor damage the catalytic converter?
Yes. If the upstream sensor reads poorly and the engine runs rich, unburnt fuel can overheat and damage the cat. Sorting a faulty O2 sensor promptly helps protect the converter and keeps fuel bills down.