Lambda sensors PEUGEOT 307 CC (3B)

For your Peugeot 307 CC (which has a different engine setup compared to the regular 307), the lambda (oxygen) sensors are located on the exhaust system and connected to the engine’s ECU by wiring harnesses routed along the exhaust pipes.

Here’s what you need to know:

- **Upstream lambda sensor (pre-catalytic converter):** This sensor is usually screwed into the exhaust manifold or the pipe just after the manifold. It measures the oxygen levels directly from the engine’s exhaust gases to help the ECU adjust the air-fuel mixture for optimal combustion.

- **Downstream lambda sensor (post-catalytic converter):** This sensor is located after the catalytic converter on the exhaust pipe. It monitors the efficiency of the catalytic converter by measuring oxygen levels in the exhaust gases exiting the cat.

- **Connection:** Both sensors have electrical connectors that usually lead back to the engine wiring harness. For the 307 CC, the connectors can be found near the sensors, wrapped in heat-resistant insulation and secured along the exhaust pipes or up near the engine bay.

- **Removal:** To replace them, you usually disconnect the battery, unplug the sensors’ connector, and use a lambda sensor socket or a 22mm wrench to unscrew the sensor from the exhaust.

- **Specific info:** A helpful part number for the Peugeot 307 CC lambda sensor is often M18x1.5 thread size. Replacement intervals are generally around 100,000 km or if the ECU throws fault codes related to lambda sensors.

So, if you’re hunting the sensors for replacement or diagnosis on the 307 CC, focus on the exhaust manifold area for the upstream sensor and the pipe right after the catalytic converter for the downstream one. Both connect electrically nearby via plugs that clip in securely🔧🚗💡