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Hi - new to this forum but hoping someone can help. The check engine light has been going on and off for the past few months. I recently took it to my trusted mechanic and he told me that my Jeep has 2 cat converters - one in the front (estimated repair $2300) and one in the back (estimated repair $800). I live in NJ and my car has about 133,000 miles on it. Problem I have is that he told me there's no way to tell which converter is making the light appear. I find that absurd! He's guessing based on the year and mileage that it's the front one, but there's no way to know for sure. So he reset the light and told me to drive it a bit more to see when it comes back on and he hopes a different code appears to shed more light on it. I'm due for inspection in June so I have some time but I def need to get it fixed to pass inspection. The code that appeared this most recent time is PO420 Cat Eff. A few months ago I took it to my same mechanic and the code read PO420 Bank1. Help! I can't shell out that much money on a guess. Thanks to anyone who can help :)
 

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Welcome,

You might ask the mechanic if they checked for exhaust leaks, or if they can tell whether the downstream O2 sensor has been replaced but the upstream sensor is old.

Either of these conditions could cause a code 420.
 

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Because of the way the way the system is designed it can be hard to tell which converter isn't working well.
The computer looks at the difference in readings from the gas going into the first catcon at the upstream sensor vs the gas coming out of the second catcon at the downstream sensor.
If there was a third sensor between the two catcons it would make it easier to see whether each catcon was working, provided all the sensors are working right.

93509
 

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2014 Jeep Patriot Sport
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Because of the way the way the system is designed it can be hard to tell which converter isn't working well.
The computer looks at the difference in readings from the gas going into the first catcon at the upstream sensor vs the gas coming out of the second catcon at the downstream sensor.
If there was a third sensor between the two catcons it would make it easier to see whether each catcon was working, provided all the sensors are working right.

View attachment 93509
Hi - new to this forum but hoping someone can help. The check engine light has been going on and off for the past few months. I recently took it to my trusted mechanic and he told me that my Jeep has 2 cat converters - one in the front (estimated repair $2300) and one in the back (estimated repair $800). I live in NJ and my car has about 133,000 miles on it. Problem I have is that he told me there's no way to tell which converter is making the light appear. I find that absurd! He's guessing based on the year and mileage that it's the front one, but there's no way to know for sure. So he reset the light and told me to drive it a bit more to see when it comes back on and he hopes a different code appears to shed more light on it. I'm due for inspection in June so I have some time but I def need to get it fixed to pass inspection. The code that appeared this most recent time is PO420 Cat Eff. A few months ago I took it to my same mechanic and the code read PO420 Bank1. Help! I can't shell out that much money on a guess. Thanks to anyone who can help :)
ive been experiencing the same problem with a 2014. It’s not effecting gas mileage or performance, but causing engine light with P0420 code to come on within 5 minutes. I live in NY and am not do for inspection until Aug. of ‘21, so I’ve been coming up with a game plan to execute as soon as it gets warmer. First, I would remove the O2 sensor in the exhaust manifold and put a back pressure gauge in its place, warm engine up, if gauge reads in excess of 2 PSI ( cat possibly plugged) it could very well be the cat. Then with a live data scan tool look at the voltage reading of of the second O2 sensor with engine warmed up and at 2000rpm the reading should be quite steady with little fluctuation, while the first O2 sensor should be fluctuating quite a bit which is normal. If the second O2 sensor is fluctuating there’s a very good chance it’s your cat. One other thing I would do is remove the heat shields sandwiching the first cat (maniverter). If you see signs of carbon on the underneath sides of the heat shields, it’s possible you manifold (with cat built in) is cracked. If it’s cracked only on the top side an attempt to seal crack could be possible, by cleaning it up and some light grinding and using a good exhaust repair epoxy. This I believe is my problem as engine heats up causing manifold to expand, but can’t confirm it yet. If it turns out to be your maniverter, there a several good remove & replace on YouTube. I hope this helps a little bit. Good luck
 

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Hi - new to this forum but hoping someone can help. The check engine light has been going on and off for the past few months. I recently took it to my trusted mechanic and he told me that my Jeep has 2 cat converters - one in the front (estimated repair $2300) and one in the back (estimated repair $800). I live in NJ and my car has about 133,000 miles on it. Problem I have is that he told me there's no way to tell which converter is making the light appear. I find that absurd! He's guessing based on the year and mileage that it's the front one, but there's no way to know for sure. So he reset the light and told me to drive it a bit more to see when it comes back on and he hopes a different code appears to shed more light on it. I'm due for inspection in June so I have some time but I def need to get it fixed to pass inspection. The code that appeared this most recent time is PO420 Cat Eff. A few months ago I took it to my same mechanic and the code read PO420 Bank1. Help! I can't shell out that much money on a guess. Thanks to anyone who can help :)
Just one other note, $2300 & $800 seem quite excessive, shop around !!
 

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Not bragging, but I've had several cars go beyond 200,000 miles on the original catcon, including my 2008 Patriot. AFAIK it's around 300,000 and still on the original. I expect to see the guy I sold it to tonight so I'll ask if he's had to change it yet.
 

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i have a 2012 and i got a recall to replace the cat. you may want to check with the dealer.
Thanks for the input Jay.

If anyone would like to check for recalls you can enter your VIN here:

Or if you have other questions, you can PM JeepCares with your VIN, they might be able to help.
 

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2017 Jeep Patriot 75th Anniversary Edition
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Hi Kristen,

Where are you in NJ? If you happen to be in the Toms River area Tooltime auto repair just off of Rt70 on Whitesville Rd is really good.
 
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