Code p0420 997 gt3
05-10-2018, 04:22 AM
#3
1st Gear
Join Date: May 2018
Location: Europe
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Check for any strange smoke from the exhaust pipe before replacing it. Burned oil or rich mixture could damage the new catalytic converters fast. Also, check the O2 sensors, a faulty O2 sensor can trick the ECM and trigger the p0420 code.
But in the most cases, it is a worn out catalytic converter. You can use some methods to trick it also if you want.
found some information here: P0420 Trouble code
But in the most cases, it is a worn out catalytic converter. You can use some methods to trick it also if you want.
found some information here: P0420 Trouble code
03-02-2019, 09:03 PM
#5
Track Day
Join Date: Feb 2011
Location: Calgary, AB
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Time to breathe some life into this P0420 thread. My car threw a CEL late last fall which the dealer said was a P0420 fault. The tech's additional comments were "unable to perform test due to catalytic converters going above specified temperature range. mutilple misfire codes set after attempting tests, suspect clogged catalytic converters may be causing misfires...".
I thought I would eliminate some of the usual suspects before going into replacing the cats so I changed out my spark plugs and installed new O2 sensors. However, the code came back within 50 miles. So on to the next step, pull off the exhaust manifolds. Looking at the part of the cat element that I can see from the downstream end doesn't reveal a clogged screen like you see on some internet pictures for "clogged catalytic converters". Is there any way to determine if the cat elements are clogged or otherwise damaged? Any other suggested things to look at as possible issues?
BTW, when the CEL came back the second time I read the OBD2 and only the P0420 came up.
I thought I would eliminate some of the usual suspects before going into replacing the cats so I changed out my spark plugs and installed new O2 sensors. However, the code came back within 50 miles. So on to the next step, pull off the exhaust manifolds. Looking at the part of the cat element that I can see from the downstream end doesn't reveal a clogged screen like you see on some internet pictures for "clogged catalytic converters". Is there any way to determine if the cat elements are clogged or otherwise damaged? Any other suggested things to look at as possible issues?
BTW, when the CEL came back the second time I read the OBD2 and only the P0420 came up.
03-02-2019, 09:09 PM
#6
I have seen a bunch of Youtube mechanics' videos that say if you use an IR temperature gun to check temp before and after the cat, a good one cat will show a significant temp increase, and a bad cat will not show much difference.