Mercedes-Benz CLK Oxygen Sensor Replacement Parts

Oxygen sensors exist on both petrol and diesel variants of the CLK, though their location and number differ by engine. Petrol engines (such as the M111, M112, and M271) typically use upstream and downstream lambda sensors either side of the catalytic converter, while diesel variants use a different arrangement tied to their emissions management. Confirm with your breaker whether they have a petrol or diesel unit to match your engine code, as the two are not interchangeable.

The W208 and W209 are entirely separate generations of the CLK with different platforms, engine families, and exhaust configurations, so parts from the first generation are very unlikely to fit the second. The W209 also introduced a facelift around 2005 which refined some engine variants, and sensors from pre- and post-facelift cars may differ depending on engine code. Always confirm the engine code from your V5 with the breaker before buying, and do not assume cross-generation fitment.

Trim level has no bearing on oxygen sensor fitment for the CLK; what matters is the engine code and fuel type, not whether the car is an Elegance, Avantgarde, or AMG-badged variant. That said, genuine AMG models with different engine codes (such as the C55 AMG or C63 AMG in the W209) do use different sensors to match their specific exhausts, so the engine code still needs to match. Ignore trim badging and go by the engine code stamped on your V5 or visible on the engine itself.

Many W209 engine codes carried across the 2005 facelift unchanged, so sensors for the same engine code can often be the same part, but you should confirm this with the breaker against both registration numbers rather than assuming. Changes to emissions tuning or catalytic converter specifications on some variants around this period can affect sensor compatibility or positioning. Give the breaker both the donor and recipient registration so they can check the engine codes match before the part is sent.

Yes — the quantity and position of oxygen sensors varies by engine. Larger V6 and V8 petrol engines in the CLK, such as those in the C240, C320, and C500 variants, use a V-arrangement exhaust with sensors on both banks as well as downstream sensors, meaning they can have four or more sensors in total. Smaller four-cylinder engines typically have fewer sensors, so always confirm how many sensors your specific engine uses and which position — upstream or downstream, NS or OS bank — you actually need.

Diesel oxygen sensors are closely tied to the emissions calibration of the engine and its exhaust aftertreatment system, so fitting a sensor from the wrong emissions era risks incorrect fuelling readings, fault codes, or a failed MOT. The CLK diesel variants sit within the Euro 3 to early Euro 4 era, and sensors from later Euro 5 or Euro 6 Mercedes diesels are unlikely to be compatible. Confirm the engine code and the exact sensor position with the breaker, who can cross-reference the donor vehicle against your registration to check compatibility.