Used Alfa Romeo 155 Lambda Sensor

Yes, petrol-engined Alfa Romeo 155s are fitted with lambda sensors as part of their engine management and fuel injection systems, used to monitor exhaust oxygen levels and help the ECU control the air-fuel mixture. The 155 was produced from 1992 to 1997, and petrol variants with fuel injection across that period used lambda sensors. However, if your 155 is one of the rarer diesel variants, it would not have been fitted with a lambda sensor in the same way, as diesel engines of that era did not use them. Make sure you know whether your car is petrol or diesel before requesting this part from a breaker.

Yes, the engine code is the most important thing to match when sourcing a lambda sensor for the 155, as different engines — including the Twin Spark and the various 1.6, 1.8, 2.0, and 2.5 V6 units — had different exhaust configurations and sensor specifications. A sensor from the wrong engine variant may have a different thread, connector, or cable length and will not fit correctly or may give incorrect readings to the ECU. Always quote your engine code to the breaker, which you can find on the vehicle registration document or stamped on the engine itself. Never rely on year alone for this part.

The 155 received a facelift in 1995 which brought some updates, but whether the lambda sensor is interchangeable across that boundary depends specifically on which engine your car runs, as the sensor specification follows the engine rather than the body revision. For the same engine code on both sides of the 1995 facelift, there is a reasonable chance the sensor is the same, but this is strong confirm-with-the-breaker territory given differences in emissions calibration and connector type that may have been introduced. Quote your engine code and registration to the breaker and ask them to check against their donor vehicle rather than assuming year-to-year compatibility. Do not rely on visual similarity alone.

No, trim level does not affect lambda sensor fitment on the Alfa Romeo 155 — the sensor is determined by the engine and its emissions specification, not by whether the car is a base, Ti, or Cloverleaf variant. A Cloverleaf and a standard 155 running the same engine code will use the same lambda sensor. What you should focus on is confirming the engine code and fuel type with the breaker, not the trim designation. Trim differences on the 155 relate to interior and cosmetic specification, none of which affects the exhaust sensor.

Yes, the 2.5 V6 engine in the Alfa Romeo 155 has a different exhaust layout from the four-cylinder units, and the lambda sensor specification — including quantity, thread size, and connector — is likely to differ. The V6 may use more than one sensor depending on the configuration, so you need to confirm exactly how many sensors your car has and which position you are replacing (upstream of the catalytic converter is the most common failure point). Always give the breaker your engine code alongside the V6 designation so they can match from a confirmed V6 donor car. Do not assume a sensor from a four-cylinder 155 will cross over.

Potentially, if another Alfa model of the same era uses an identical engine with the same exhaust configuration and sensor connector, there may be a match, but this is not something to assume without checking. Sensor thread pitch, cable length, and connector type must all be identical, and these details follow the engine code rather than the badge on the car. A breaker experienced with Alfa Romeo stock will be able to cross-reference donor vehicles by engine code and advise whether a sensor from, say, a 156 or GTV of the same period is compatible. Always verify against your specific engine code rather than brand alone.