What is the cracking sound when I accelerate? on 2002 Lexus RX300

I drive a 2002 Lexus RX300 and I hear a "cracking" sound when I accelerate. What could be causing this?

by in Stafford, TX on April 08, 2013
1 answer 1 comment
ANSWER by on April 09, 2013
exhaust leak. I would guess exhaust manifold has a crack
COMMENT by on April 09, 2013
Thank you! Could a bad O2 sensor cause that as well?