Catalytic Converter

[N80]

I have a 2003 Nissan Murano with 130k miles on it. Now the check engine light is on and the dealer says the catalytic converter is 'bad' and needs to be replaced. At $1200. It runs fine. Get a little more smoke than usual when it starts and starts aren't as brisk as when it was new, but otherwise everything is fine.

I'm all for protecting the environment and all that but $1200 is more than I'm willing to spend to keep Al Gore happy.

I live in a state that has no vehicle or emissions inspections (thank goodness).

So, my only reason to replace this thing is make sure the car runs properly. What exactly happens when a catalytic converter goes bad? Does it impeded exhaust flow? If it has no real impact on performance or longevity then I'm not going to bother. If it is important for those things then I'm going to sell it.

We love the performance and form factor of this car; its my wife's. And I've always been a big Nissan fan, but this Murano has not been as flawless as all my others and there's a lot of noise on the web about the catalytic converters going bad on the Murano. So if it really needs replacing its good by Murano, goodbye Nissan and I will have to look elsewhere for an AWD station wagon. Maybe Subaru.

 

[RobertN]

They tend to clog. I had one do that on my old truck. It was on a trip, about 4 hours from home. Got to where it would idle, but no much more. I wound up unbolting the front of the catalytic converter, and driving 4 hours home with an open exhaust.

I fixed it later before a smog check. Until the smog check, I got a bar and punched the stuff out.

 

[ray66v]

As Robert said it is probably starting to fail.

They usually get melted from fuel burning inside.

Baring a manufacturing defect, there is an underlying problem causing the failure. (i.e. some sort of ignition problem).

If it is going, eventually, it will drive like the brake is on.

When this happens there, is a risk of igniting the carpet, and padding.

Start it up cold, and drive it for 5-10 minutes, turn it off, and open the hood. If you hear a lot of metallic popping and ticking noises, the exhaust system is over heated. That means the converter is failing.

Have an aftermarket converter installed, for a lot less money, after the reason for failure is determined, and repaired.

 

[Wis Bang]

Depending on the design you should be able to get a muffler shop [Mineke] to install an aftermarket unit. Speed houses like Jeggs or Summit sell high flow cats for a few hundred, price one on line to get a ballpark for the cost...try NAPA or Advanced Auto Parts on line to get a ballpark; I'll bet you can get one for alot less than the dealer.

If it doesn't plug up the oxygen sensors [before and after] will make the fuel delivery system run very screwy probably making it burn more fuel and run less efficient...on OBD II [post '96] autos it's part of the system and you need to realize it.

 

[kenmac]

when mine went bad. It set the code cat. converter below threshold. Meaning the cat was burn / burning out not capturnig enough stuff.. I didn't replace my cat. To keep the light off I bought a spark anti fouler & installed it where the sensor goes . Then, I screwed the sensor into the anti fouler. This keeps most of the sensor out of the exhaust stream. Caution,,, in some cases you may get another code,,, lean mixture. May be worth a try. I believe it is a 10 mm anti fouler

 

[427ricky]

Just cut it out and put a peace of pipe in place. Take your old cat to the local scrap yard it's probably worth about $100.

 

[westcliffe01]

You should check into whether the Cat has a federally mandated durability requirement. Many systems have a mandated 10 year durability requirement. The O2 sensors are not covered, but the catalyst is. Chrysler / Jeep had to recall and replace millions of catalysts because they were not durable.

Catalysts can degrade at the metallurgical level (sintering of the platinum or palladium) or mechanical (typically the support mat giving out from thermal exposure). The catalyst (precious metal) can also be poisoned by exposure to lead or other metals in the fuel as well as certain oil additives, which should not be in the OE specified oil, but may be in aftermarket products or fuel additives.

OE testing usually has to extend well past 130k, since 150k is the mean distance to failure and that number includes data from much older vehicles.

The only time warranty may not apply is when one has driven for many thousand miles with a check engine light (they can tell by scanning the ECU). Worst case scenario, get an aftermarket catalyst for less than $200.

I have a 2003 Nissan Murano with 130k miles on it. Now the check engine light is on and the dealer says the catalytic converter is 'bad' and needs to be replaced. At $1200. It runs fine. Get a little more smoke than usual when it starts and starts aren't as brisk as when it was new, but otherwise everything is fine.

I'm all for protecting the environment and all that but $1200 is more than I'm willing to spend to keep Al Gore happy.

I live in a state that has no vehicle or emissions inspections (thank goodness).

 

[N80]

Thanks guys. Will look into aftermarket units. I knew they would less expensive but did not know by how much.

I took the one off my first Nissan pickup. It bolted on and I bought a replacement tube ("for racing purposes only") that bolted back in place.

I've never been under this Murano so I don't know if the cat is bolted on or welded on. Even if it is a bolt on there would have to be a manufactured pipe for me to replace it with. I don't weld or fabricate and I'm assuming the muffler shops aren't allowed to pull them.

 

[N80]

Doing a little research. Apparently this car has two catalytic converters. One right at the manifold and one in the rear. (Or maybe it has 3 ???? since its a V6 and has two manifolds????) I wonder if they can tell me which one needs replacing. The aftermarket ones for the rear have no port for the O2 sensor so I'm assuming its the one at the manifold that has gone bad.

Very confusing.

I'd love to pull them off and gut them. What would that do to the O2 sensor and what effect would that have?

Thanks guys. I must say the more I read about this problem with this specific model the more I'm inclined to bite the bullet and get rid of it. I have no car payments right now and I'm no longer into cars and it would stink to have a payment. I usually drive my cars and truck until the die or get totaled but this one is starting to give me a bad vibe. Just got through spending $700 for new front struts and axle seals.

Oh, the emissions warranty is only for 80k miles.

 

[westcliffe01]

Looks like the law requires 10 years / 100k miles for an SUV, so you missed it by 30k miles...
EPA regulation
\5\ At the time this durability procedure was effective, the
useful life mileage for light-duty vehicles was 100,000 miles. Refer
to 40 CFR 86.1805-04 for current useful life mileage values.
On a Japanese vehicle, I would expect you would likely have a fabricated manifold with a close coupled catalyst, with a second catalyst in the "toeboard" or underfloor. Typically the manifold catalyst is a fully welded assembly and requires replacement of the manifold too (its in 1 piece).

If it is not physically damaged, I would suggest going to a non OE service center to have them read the PCM codes. If your O2 sensors have never been replaced thay are certainly due. Usually even getting to 100k is a miracle. My previous Audi needed new sensors every 75k, supposedly regular gasoline here has a high level of sulphur and poisons the O2 sensors.

The first O2 sensor in the system (closest to the exhaust port) is the most critical, but all of them do need to work. If it is O2 sensors that you need it should be $300 at the most for 4 sensors + some labor to fit them and it will run as long as the engine is likely to live.