Vauxhall Signum Oxygen Sensor Replacement Parts

Yes, all petrol-engined Signum models have at least one oxygen sensor (lambda sensor), fitted in the exhaust system to help the ECU manage fuelling and emissions. Diesel Signums also have exhaust gas sensors related to emissions management, though the exact sensor types differ from petrol setups. When searching, confirm with the breaker whether you have a petrol or diesel and supply your registration, as the sensor location and specification vary by engine code.

The Signum ran from 2003 to 2008, with a facelift arriving around 2005, but the key fitment factor is the engine code rather than the facelift year itself — many engines carried across the facelift with the same sensor specification. That said, some engine variants changed or were introduced at the facelift, so a sensor from a pre-facelift car is not automatically a safe swap to a post-facelift one. Name the engine code to the breaker alongside your registration and they can confirm whether the part is a true match across that 2005 boundary.

Trim level makes no difference to oxygen sensor fitment on the Signum — Elegance, Design, and Vector were specification packages affecting interior, wheels, and equipment, not the exhaust or engine setup. What matters is the engine code and fuel type, which can be the same across all three trims. Focus on matching the engine code shown on your V5C or confirmed by the breaker against your registration.

The Signum shared its platform and many engines with the Vectra C, so there is a reasonable chance of crossover for sensors on matching engine codes, but this is strong confirm-with-breaker territory. Sensor position, connector type, and thread pitch all need to match, and small production changes mean a visually identical sensor may not be electrically compatible. Give the breaker both registrations and the engine codes from both vehicles before agreeing a purchase.

The oxygen sensor works in conjunction with the catalytic converter, and on multi-sensor setups there will be a pre-cat (upstream) and post-cat (downstream) sensor, which are different parts with different roles. Make sure you know which sensor position you need — upstream or downstream — as well as your engine code, before approaching a breaker. Catalytic converter and sensor interchange specifics are best confirmed with the breaker against your exact registration rather than assumed from year or trim alone.

Diesel Signums do not use a narrowband lambda sensor in the same way petrol engines do, as diesel combustion works differently and does not require the same closed-loop fuelling feedback. They may have other exhaust sensors such as exhaust gas temperature sensors or NOx sensors depending on the engine variant and emissions standard. If you have been quoted an oxygen sensor for a diesel Signum, it is worth confirming with the breaker exactly which exhaust sensor is needed for your specific engine code and year.