2004 Hyundai Elantra Q&A

2004 Hyundai Elantra Question: P0421- Warm up catalyst below threshold (Bank 1)- where is this located?

I have a 4 cyc single exhaust 2004 Hyundai- I have one 02 sensor on top of the exhaust manifold; another one just below the flange of the exhaust manifold where the exhaust pipe connects to the exhaust manifold. -
Answer 1
Your warm-up catalytic convertor is in your exhaust manifold -