What does code P0421 indicate that I should have repaired?
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2003 Hyundai Santa Fe Question: Check Engine Code P0421
Answer #1Bret Bodas April 09, 2009, 12:40Master
A code will never point to one item as needing replacement, it takes a diagnosis of the related systems to determine the fault. Here are some things to check for that code:
A code P0421 may mean that one or more of the following has happened:
* The catalytic converter is no longer functioning properly
* An oxygen sensor is not reading (functioning) properly
* A spark plug is fouled up
Answer #2poss April 12, 2010, 09:43Rookie
read it somewhere in the manual.timing belt i think.
Replyed ohmnes, June 28, 2013, 08:24Rookie
why is it so important to change the timing belt?????