BMW 11781739845 Oxygen Sensor

The sensors are installed at the front and rear of the catalytic converters. Prior to sensor removal, use a BMW scan tool to read out and clear ECM fault codes. To avoid damaging oxygen sensors, remove them before exhaust system or manifold removal, and do not mix up oxygen sensor connectors; mark connectors before disassembling. For a 6-cylinder engine, remove the intake manifold cover and separate post-catalyst oxygen sensor connectors. Working at the right side of the engine above the exhaust manifolds, remove the oxygen sensor harness connectors from brackets, then separate connectors. Use a slotted 22 mm socket to remove the oxygen sensor. To access post-catalyst oxygen sensors, raise the vehicle and support it safely, then remove the front end reinforcement, ensuring not to drive the vehicle without it installed to prevent damage to the chassis or front end. For post-catalyst oxygen sensors, use a crow-foot wrench for removal. For a V8 engine, raise and support the car for access to the exhaust system and remove the oxygen sensor with a crow-foot wrench. When installing, coat sensor threads with anti-seize paste, noting that new sensor threads come pre-coated. Avoid overusing anti-seize paste and ensure the sensor tip remains uncontaminated. Finally, make sure sensor electrical harnesses are routed as before and connected correctly.

Replacement of oxygen sensors at specified intervals ensures that the engine and emission control system continue to operate as designed, while extending the replacement interval may void the emission control warranty coverage. Oxygen sensor replacement is covered in the section on the exhaust system.

The handling of evaporative fuel vapors from the fuel tank has been made tighter with additional ORVR venting control and enhancement of the fuel tank leakage detection system. The fuel vapour recovery system during refuelling collects and stores hydrocarbon fuel vapour where pressure from the incoming fuel forces the vapours through the breather hose to a container, then into the charcoal canister thus enabling the system to breathe in the right components. To deal with the exhaust emissions, there are four oxygen sensors, two pre-cat and two post-cat. The post-catalyst sensors are traditional heated zirconia systems that produce a steady voltage when running properly, while the precatalyst sensors are Bosch LSU planar wideband types which make use of zirconium oxide ceramic layers for brisk reading over a broad air-fuel mixture range. The sensors especially intended for best operation need the ambient air as a reference gas and it enters the node through the harness connectors. If it malfunctions, the connector ought to be inspected for contamination, cleaned thoroughly and the harness reconnected in order to remove oxidation from the pins.