# 2005 Nissan Pathfinder SE Catalyst converter V6 4.0L



## inchica2009 (Jan 23, 2016)

I need some help . If anybody can tell me how many catalyst converter this 2005 Nissan Pathfinder SE Catalyst converter has?

I did OBD scan and it says catalyst conver bad, under below threshold.

I went underneath the car and see total two. I see two catalsyt for sure but I am not sure other two. are those also catalyst converter also hooked up to each converter also? Its little bit smaller than catalyst converter but I am not sure if those two are also catalyst or not.

Car is not speeding up more than 20mpg now. Need to change all my catalyst converter but not sure if I need to change or 4 !!!!



how are you doing? Can you please tell me how any catalyst converter 

2005 Nissan Pathfinder SE Catalyst converter V6 4.0L has?


I see two catalyst converters. Than I see one small thing looks like catalyst converter hooked up to each catalyst converter.

Are those small thing also catalyst converter?


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## smj999smj (Jan 1, 2006)

There are four catalytic converters. The upstream converters are the ones that are monitored by the ECM (which means they sit between the upstream and downstream oxygen sensors) and they bolt directly behind the exhaust manifolds using a 3-bolt flange (actually, two studs and one bolt w/nut). Then, after the converter, is a front pipe with integral post-converters. The post-catalytic converters are not monitored and rarely get clogged, as the upstream converters, in a way, act like "filters" before the exhaust gets to the post converters. Anything that would clog a converter would get trapped in the upstream converter before it would ever reach the post converters. 
Catalytic converter codes, specifically P0420 and P0430, may indicate a converter is bad, but doesn't usually or necessarily mean the converter is restricted or clogged. Those codes mean the converter(s) is/are inefficient at breaking down the exhaust gases. This is determined by the ECM, which compares the rich-lean cycling frequency of the upstream oxygen sensor (before the front converter) to that of the rear oxygen sensor (after the front converter). To be more specific, the front oxygen sensor is really not an oxygen sensor, but an "air/fuel ratio sensor." It's similar in function to an oxygen sensor, but reads in a much narrower range. 
I would perform an exhaust backpressure test to make sure the converters on both banks are actually in need of replacement due to restriction. Catalytic converters are expensive and a pain to replace (the upstream ones, anyway) and not something you want to replace if it's not actually bad. Also, there are other things that can cause low power or poor acceleration and set catalyst efficiency codes, for example, a fuel pump with low fuel pressure, which could cause a lean condition that would set catalyst codes on both banks. Did you happen to check fuel pressure?
Another thing to keep in mind is that if one or more of the catalytic converters actually ARE clogged, what caused them to do so? Could it be burning oil or dumping fuel? You'll want to inspect the inlet side of the catalytic converter substrate for signs of contamination. 
Genuine Nissan, upstream converters are over $600. Rockauto.com sells direct-fit converters, like Walker and Bosal, for much less. BUT, keep in mind that some states only allow genuine Nissan or C.A.R.B. approved catalytic converters.
Hope you get her straightened out!


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## inchica2009 (Jan 23, 2016)

Both side catalyst converter was broken inside.One was totally hollow one had broken screen inside. When unplugged the catalyst converter lot of smoke seemed like burning oil came out.Car was burning and dripping oil where the catalyst converter was disconnected.Wondering how gasoline or oil was entering the exhaust pipe.

Is it possible that there is head gasket leak somewhere and leaking oil in the exhaust pipe?


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## inchica2009 (Jan 23, 2016)

It always gave me P420 code since I bought the car. But car never had any issue driving. Last week it wont spped up and said P0300 with multiple cylinder misfire. So I went ahead and changed all the spark plugs. All the ignition coils seem to be fine also. White smoke was coming from tail pipe.

After disconnecting both catalyst converters, oil was burning and lot of black smoke was coming where I disconnected the pipes.It seems. Also Both U-joints were shot.Has new -joints now. Car seems like speeding up. But I am still not sure if anything wrong with my head gasket or not.I thing I also saw white stuff in motor oil.

Is my head gasket bad? Any possibility?


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## smj999smj (Jan 1, 2006)

It could be a bad head gasket. White streaks or a white, custard-like "goop" in the oil is a sign of water (or engine coolant) mixing with the engine oil. You might want to check for signs of oil in the engine coolant. Another condition that can occur is when the catalyst substrate breaks down and gets sucked back into the combustion chambers and scores the cylinder walls, resulting in an oil-burning engine. This can happen because the engine uses the variable valve timing capability to crack open the exhaust valve during an intake stroke to suck in exhaust gas back into the combustion chamber instead of doing it the more conventional way of using an EGR valve. Either way, a compression and cylinder leakdown test would be in order. If the engine is burning oil or coolant, it will quickly ruin the new, catalytic converters.


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## inchica2009 (Jan 23, 2016)

Ok. I got both catalyst converter off. No smoke is coming out from anywhere anymore. Car drives smooth.

But car won't speed up more than 40mph.

Is it possible that car won't speed up more than 40mpg or higher because of not having the catalyst converter connected?


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## smj999smj (Jan 1, 2006)

I doubt it, assuming you are talking about the front catalytic converters. You might want to recheck it for codes to see if there are any cam or crank position codes. Check the fuel pressure wouldn't be a bad idea.


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## M.A. (Jul 13, 2021)

inchica2009 said:


> Ok. I got both catalyst converter off. No smoke is coming out from anywhere anymore. Car drives smooth.
> 
> But car won't speed up more than 40mph.
> 
> Is it possible that car won't speed up more than 40mpg or higher because of not having the catalyst converter connected?


Hi, did you remove the catalyst converter? How about the O2 sensors? And did you had any issues with emission test?

I am planning to buy a pathfinder 2006. I know its quite old but the owner maintained the vehicle well. But, recently Nissan service center quoted them to replace the whole assembly of the exhaust including all cat for $4000. The cars value is not even near to that so they had it double checked, and the mechanic removed both front cat. Im just wondering if this will be fine or will be an issue later on. Thanks.


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## smj999smj (Jan 1, 2006)

M.A. said:


> Hi, did you remove the catalyst converter? How about the O2 sensors? And did you had any issues with emission test?
> 
> I am planning to buy a pathfinder 2006. I know its quite old but the owner maintained the vehicle well. But, recently Nissan service center quoted them to replace the whole assembly of the exhaust including all cat for $4000. The cars value is not even near to that so they had it double checked, and the mechanic removed both front cat. Im just wondering if this will be fine or will be an issue later on. Thanks.


By "remove" the front cats, do you mean eliminated or gutted? If so, this causes the ECM to run the mixture lean, so the ECM needs to be custom tuned to compensate for this. UpRev is the only company I know of that does it.


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## M.A. (Jul 13, 2021)

smj999smj said:


> By "remove" the front cats, do you mean eliminated or gutted? If so, this causes the ECM to run the mixture lean, so the ECM needs to be custom tuned to compensate for this. UpRev is the only company I know of that does it.


All sorted, thanks. It was the exhaust pipe. It got damaged when the Nissan service center cleaned the fuel line to rectify an issue with vibration on the initial start up of the engine. They damaged it and is recommending to change the whole assembly including the cats. We got it checked elsewhere and was told that the cats are still ok and there are no O2 fault codes as well. Now, the path has a deeper sound because of the damage on the exhaust pipes. I will leave it like that for the mean time. Thanks.


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