2005-2014 Mustangs Discussions on the latest S197 model Mustangs from Ford.

Cats code question

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Old Jul 17, 2018 | 02:34 PM
  #1  
68XR7's Avatar
68XR7
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Default Cats code question

Recently, I replaced the plugs and wires on my 2007 w/4.0. I noticed that it started running badly and my check engine light came on. The code scanner indicated that I had a misfire in #2 cylinder, and a cats error.
I replaced the plug wires again, reset the code, and drove the car on the highway with no issues, for a while at least, until the check engine light came back on. It showed a cats error on the #1 cylinder bank.
I was wondering if this cats problem is a result of the bad plug wire? If so, can I expect this error to correct itself, after I drive the car, and clean out the cats? The car runs well and produces good power. Any insight is helpful.
Old Jul 18, 2018 | 01:33 PM
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Derf00
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How many miles on the car?

What made you replace the plugs and wires? Regular maintenance?

What brand of plugs and wires did you install? What gap did you use on the plugs?

A misfire could cause a cat error as you'd be dumping unburned fuel into the cat that would lead to overheating of the cat. An overheated cat could melt and lead to continous codes being thrown until the Cat is replaced or removed and the sensors turned off.

What is the exact error?
Old Jul 22, 2018 | 05:44 PM
  #3  
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68XR7
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Originally Posted by Derf00
How many miles on the car?

What made you replace the plugs and wires? Regular maintenance?

What brand of plugs and wires did you install? What gap did you use on the plugs?

A misfire could cause a cat error as you'd be dumping unburned fuel into the cat that would lead to overheating of the cat. An overheated cat could melt and lead to continous codes being thrown until the Cat is replaced or removed and the sensors turned off.

What is the exact error?
You are absolutely correct. I replaced the plugs and wires with new Motorcraft parts. After getting a misfire code on number 2 cylinder, I pulled the wire off and checked the resistance, and found it to be too high, indicating a defective wire. I returned the bad wires, but it may have been too late, i think that it fried the #1 cats. I no longer have the cylinder misfire, but i do have a permanent cats code. My code reader showed that the right cat appears to be doing nothing.
Thanks for responding, I appreciate it.
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