Bingo! That was one of my guesses
Yea the O2 sensor is aka the lambda sensor; that's what it's known as in Europe. Here's the thing: I think Al is wrong. "Lambda" and "Lambda Control" both mean the same, and have no reference to the relay. His diagnosis should trigger a code 1264: O2 sensor heater malfunction. That will usually indicate that the relay is faulty. A code 1222 however, indicates the sensor is operating beyond its normal range. You can verify this with anyplace that lists the OBD I code system, whether it be the Bentley, Pelican, Unnofficial BMW, etc. But to be on the safe side, I would replace both. You'll be able to get the O2 sensor from Pep Boys or anyone online that caters to BMW's. The relay you want is the Bosch orange relay, Pelican's part # is 61-36-1-378-238-M14.