Second Hand Mercedes-Benz CLA Oxygen Sensor

Yes, but only on petrol-engined CLA variants — the lambda (oxygen) sensor is part of the exhaust management system on petrol engines and is essential for the ECU to control fuelling and meet emissions standards. Diesel CLAs do not use a conventional oxygen sensor in the same way; diesel exhaust management instead relies on NOx sensors, a diesel particulate filter (DPF), and related components rather than a wideband lambda probe. If you drive a diesel CLA and are chasing an emissions or exhaust fault, you are almost certainly looking for a NOx sensor or DPF-related part rather than an oxygen sensor — confirm the exact fault code with your garage before ordering.

The C117 first generation ran from 2013 to 2019 (with a facelift in 2016), and the W118 second generation launched in 2019 — these are completely different platforms with different petrol engine families, so an oxygen sensor from a C117 is very unlikely to be a direct fit on a W118. The key things to match are the engine code (for example M270 or M133 on the C117 versus M282 or M139 on the W118) and the sensor position (pre-cat upstream or post-cat downstream), as connector type, thread pitch, and harness length can all differ. Always confirm the engine code from your V5C or by providing your registration to the breaker before buying.

No, trim level does not affect which oxygen sensor is fitted — AMG Line, Sport, Urban, and any other trim grade all share the same exhaust and engine management hardware if they have the same engine code. What matters is the engine code (e.g. M270 1.6 or 2.0 petrol), the sensor position (upstream before the catalytic converter, or downstream after it), and the model year's emissions standard (Euro 5 or Euro 6), not what badge is on the boot. You may find cosmetic differences between cars from different trims, but the sensor itself is determined entirely by the engine and emissions specification.

Yes, this can matter — Euro 6 variants (broadly from 2015 onwards on C117 models following mid-cycle updates, and all W118 models) can use revised engine management calibrations and sensor specifications compared to earlier Euro 5 cars, even with the same engine displacement. A sensor from the wrong emissions era may physically fit but could cause fault codes or fail an MOT emissions test if the output characteristics do not match the ECU's expectations. Provide your registration and engine code to the breaker and ask them to confirm the emissions specification of the donor vehicle before purchasing.

The C117 was facelifted in 2016, and while the core engine families carried over, there were updates to engine management and emissions calibration around this period that could affect sensor compatibility. Naming the facelift boundary is straightforward, but whether the specific oxygen sensor interchanges cleanly across that 2016 boundary depends on the exact engine code and sensor position, and this is best confirmed with the breaker against both registrations. Give the breaker your registration number and ask them to check the donor car's engine code and build date to be sure.

Petrol CLAs typically have at least two oxygen sensors per bank — one upstream (before the catalytic converter) and one downstream (after it) — and these are not interchangeable with each other as they serve different functions and often have different connector types or cable lengths. Getting the position wrong (upstream versus downstream, and on which side of the engine if applicable) is a common mistake that will result in the wrong part arriving. When contacting a breaker, specify your engine code, the sensor position (upstream or downstream), and your nearside or offside if relevant, to make sure you get the correct unit.