Close
Q:

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

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
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.
(1) Answer