Not necessarily! Your 4 cylinder engine has one pre-cat O2 sensor and one post-cat O2 sensor.
H Hani · Registered 2002 330i, 2000 323i Joined May 31, 2008 · 1,043 Posts #4 · 2 mo ago View full thread Not necessarily! Your 4 cylinder engine has one pre-cat O2 sensor and one post-cat O2 sensor.