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Discussion Starter #1 (Edited)
Hey, I struggle to grasp if my sensor is ok or not, I just bought my 2002 coupe from an owner who had it for over 11 years and i just got a check engine P0420 i cleared the code and after some driving (like maybe 100+ km) the code came back so I googled some and started to check the sensors. I have 2 videos:
First is before any kind of touching anything (in the video if the green squares are at the bottom of the button it means it runs on LPG now):
Second after i disconnected the sensor tried to start the car (it didn't start), and then connected it back up and started the car:

I also checked the fuel thing and it was all the time on 99.2% for the sensor 2 should it be like that ? //edit <=
The car runs on petrol (gasoline) and gas (LPG). There is some white smoke coming from one of the exhaust pipes but not to much of it.
Is the sensor bad or it works like it should? Or is the cat bad ?

Edit: I checked again and it appears that the o2 sensor 2 only makes a some kind of sinus graph only on LPG when the engine is fully heated is it a problem with LPG adjustment ?
Some other pics:
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135969
 

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So, I have some experience with propane only motors (like forklifts and generators) but I have absolutely zero experience with dual fuel gasoline/propane conversions or vehicles. We just dont have that here.

I would run it with LPG turned off, and see if the code comes back.

Clear it, and run it with LPG turned on, and see if the code comes back.

If it comes back under both conditions, Id replace the O2, then the cat if that doesnt work. But like i said, i have no experience with that setup. You might spend some money before you have the right answer on this one.
 

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Discussion Starter #3
Thanks for answering @Faulcun I tested some and it appears that something is off with my LPG installation (i borrowed a sensor) either it has to be adjusted or replaced because It has problems with acceleration and it drops RPM really fast if i stop pressing the acceleration pedal, it's so bad that when i get to neutral from 4k+ rpm the engine dies on me. If anyone knows if I can fix this by adjusting the gas (let's say it's not broken because my wallet doesn't like it ) and by this I mean the acceleration and P0420 would love to get the info how ( so the mechanics don't scam me into unnecessary installation replacement ), thanks in advance.
 

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Don't know anything about LPG setups but first thing that comes to mind is doing away with the LPG setup and just run on regular gasoline lol
 

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Don't know anything about LPG setups but first thing that comes to mind is doing away with the LPG setup and just run on regular gasoline lol
Thats easy to say here in the united states. Due to ethanol production, and president trump helping to make this country self sufficient on energy, we are now exporting cude oil instead of importing. Because of this, our fuel prices are relatively low, depending on what state you are in. The largest cost to our fuel at the pump are taxes.

In other countries, such as Poland where OP is from, gasoline costs $4.41 per gallon, and LPG costs about $1.98 per gallon. Would you rather spend $60 to fill up, or $25?
 

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So, I have some experience with propane only motors (like forklifts and generators) but I have absolutely zero experience with dual fuel gasoline/propane conversions or vehicles. We just dont have that here.

I would run it with LPG turned off, and see if the code comes back.

Clear it, and run it with LPG turned on, and see if the code comes back.

If it comes back under both conditions, Id replace the O2, then the cat if that doesnt work. But like i said, i have no experience with that setup. You might spend some money before you have the right answer on this one.
While later posts seem to rule out the sensor (O2 sensor), I will add that the 1st thing I do is check for exhaust leaks. Leaks can trip a P0420.
 
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Discussion Starter #9
So some time went by and it seems to look like it only happens on LPG like the o2 sensor insinuates. I was at local Car-LPG installation shop and they told me they can regulate the installation and it should fix the problem, so until I get from the info from previous owner about what kind of model the installation is I can't fix the issue low-cost.
 

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A while back i would get a P0420 code pop up for me on my other car and after going through all of the possibilities i eliminated it down to the catalytic converter being clogged ran some cataclean through it and it seemed to run better for awhile, now the car is back in limp mode again, so i found a new cat on amazon haven't gotten around to replacing it yet, focusing on my tibi for now.
 

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While later posts seem to rule out the sensor (O2 sensor), I will add that the 1st thing I do is check for exhaust leaks. Leaks can trip a P0420.
Yes i forgot to mention that! Exhaust leaks near or upstream from the O2 can cause erratic behavior or at the minimum throw off values enough to cause a catalyst code.
 

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Yes i forgot to mention that! Exhaust leaks near or upstream from the O2 can cause erratic behavior or at the minimum throw off values enough to cause a catalyst code.
Pretty much anything before his #2 sensor i believe isnt it @Faulcun? After that, i couldn't see it causing a problem because i dont think his #2's read the back pressure off his mufflers, could be wrong though
 

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Pretty much anything before his #2 sensor i believe isnt it @Faulcun? After that, i couldn't see it causing a problem because i dont think his #2's read the back pressure off his mufflers, could be wrong though
I would say anything within 6 inches after could be suspect.
 

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Like a pin hole leak or something close to that? It's insane how to us what we might consider to be a minor or insignificant thing to a vehicle can turn out to be something pretty major for that vehicle.
 

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Like a pin hole leak or something close to that? It's insane how to us what we might consider to be a minor or insignificant thing to a vehicle can turn out to be something pretty major for that vehicle.
Its based on how exhaust pulses work. Every time the exhaust valve opens and expels exhaust gas, thats a pulse. If you put your hand near the exit, you can feel the pulses. Every time a pulse passes through the exhaust, there is a pocket of vacuum behind it. A proper designed exhaust is designed to take advantage of that which can help pull the next pulse out more efficiently.

When there is a leak in the exhaust, you can pull fresh air in through the leak during that vacuum pocket.
 

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Yes i forgot to mention that! Exhaust leaks near or upstream from the O2 can cause erratic behavior or at the minimum throw off values enough to cause a catalyst code.
Agreed, thus my comment....exhaust leak can be upstream/downstream of O2 sensor....while we "assume" positive pressure within the exhaust, there are times of lower pressure...thus sucks in ambient air and can trip a P0420...,easy test, jack car up, engine running, someone blocks off tailpipe/pipes, someone else listens/feels for leaks.....local shop I work for, they went down this road, new Y-pipe had a bad downstream sensor bung weld.....noted by soot by the weld. I did a quick clean and Oxy/Acet gas weld to fix new bung.....no issues since AFAIK......2 years ago....
 

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Thats easy to say here in the united states. Due to ethanol production, and president trump helping to make this country self sufficient on energy, we are now exporting cude oil instead of importing. Because of this, our fuel prices are relatively low, depending on what state you are in. The largest cost to our fuel at the pump are taxes.

In other countries, such as Poland where OP is from, gasoline costs $4.41 per gallon, and LPG costs about $1.98 per gallon. Would you rather spend $60 to fill up, or $25?
How much is nitrous in Poland?
 

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I have no idea. There are no fuel station statistics on that because nobody daily drives their car on pure nitrous.
 
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