Rough Idle with code P0420
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11-04-2010, 11:37 AM
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Rough Idle with code P0420
My truck (2005 5.4) has had a rough idle for about the past seven months. The CEL has been on for probably six. Sometimes it would go off and come back a week later. I finally got around to reading it and got code P0420 (Catalytic Efficiency Below Threshold). Does this mean my cats are bad? And would that cause a rough idle? I have already changed my plugs to champions less than a year ago
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James Bibb
Ford Inline Six, 200, 250, 4.9L / 300
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05-27-2012 06:24 AM
