I guess an exhaust leak might affect the functioning of the O2 sensor.

Still, it only takes a minute or two to get the code(s).

Do it and post the result.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".