I had replaced a upstream Oxygen Sensor on it several months ago (on my '04 WRX) and everything went well.
Fast forward to about a week or two weeks ago got a MIL/CEL, and said to myself WTF now...got my scanning
tool out and it read P0420 trouble code (Cat. Converter, [possibly downstream O2 senor] below threshold B1/B2).
So I'm thinking...I had recently crossed a flooded exit ramp on a highway which submerged the whole exaust system
for about 3-5 seconds and I am wondering if water got in the Cat Converter/O2 Sensor and if that had caused the
problem...or maybe not...suggestions ?
Thanks for any help/suggestions.