P0420 code and exhaust leak

Joined
Jan 3, 2012
Messages
6,023
Location
Florida
F150 check engine light came on yesterday. Did a scan with Torque Pro and P0420 Bank 1 came up. Looking though whatever I can see on the app the 02 sensors seemed to be operating okay. The offending ratio was barely out of range. Heat gun showed hotter behind the cat but it was hard to get good readings in the driveway with the position of the cat and it was at idle since I didn't have an extra body. Getting under the other side I could hear what sounded like a small leak. Power and economy have not changed. How likely is the leak the culprit? Oddly, I also just got the truck back yesterday from having the speed sensor recall done, and had them look at an airbag issue. The computer was reset it appears. Could the software update have changed the acceptable range?
 
I would take it back to the dealer and explain your problem, as you have done here. They may have inadvertently done something to cause the problem.
 
Reset the code and see if it comes back. If it does I'd consider a defowler for the o2 sensor. I did that on a 05 accord and the P0420 code has never returned.
 
Originally Posted by 2010Civic
Reset the code and see if it comes back. If it does I'd consider a defowler for the o2 sensor. I did that on a 05 accord and the P0420 code has never returned.

I reset it last night. It came back.
 
Originally Posted by Charlie2015
There is a federally mandated 8 year / 80k mile warranty on converters.

120K
 
Probably a broken manifold bolt. A precatalyst exhaust leak can certainly cause low catalyst efficiency codes. It wouldn't be the first time a new calibration caused DTC's because different failure thresholds.

If you know someone with HP-Tuners.....This can be remedied with a few keystrokes
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The last few times I've driven the truck I've noticed the offending ratio was back in range. Light went off today on it's own.
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