# Help with 2000 Maxima (check engine light) error code P0430



## theonyxserpent (Nov 18, 2009)

Hi, I recently bought a 2000 Maxima with 130,000 miles on it. Just yesterday, the check engine light came on, so I took it to AutoZone and they told me it was error code "P0430: Catalyst Efficiency Below Threshold". He told me I would need a new catalytic converter, but there are 3 of them (PreCat, Y Section, and Rear I think) and he didnt know which one it was just from the diagnostic test. I've been reading online about these same issues with the same vehicle, and some say its an O2 sensor, and some say it could be my Mass Air Flow Sensor. I asked him if that code SPECIFICALLY meant that I needed a cat, (or was this just the most expensive problem he just diagnosed on his own). Does anyone know about this specific code? Do you know what I would need to replace just off that code? I just dont want to fix/replace something that is not fixing my main problem, I'm working with a limited amount of $$ right now, and I want to fix the right thing. Most people are saying its the cat.


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## nelsito65 (Jan 12, 2007)

It is one of the worst code to have its cause pinpointed. It looks like you have a California spec maxima, which have two pre-cats (front and rear) and a catalytic converter. Some people swear by just replacing the front pre-cat and be done. It is the one closest to the front of the vehicle. I've been living with that code for the last 14 months that I've owned my present maxima (I had a 98 before this one). I replaced the bank 2 sensor 2 and it didn't do the trick. Some people recommend to at least trying a can of catalytic converter cleaner in a tank of gas, so I did, hoping for something to happen and it didn't do anything either. One of these days I'll bite the bullet and spend the $200 for the pre-cat and see if that gets rid of the code.


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## Idtype1 (Nov 20, 2009)

California, Nissan 2000 GLE, 163K, Original owner. Ex Nissan HQ Employee in Torrance, CA.

Like everyone else, starts with a shake. (SES)

All 6 Coils replaced (SES goes away)
SES (P0430) - All G5 Maxima owner knows this one. Not going to fix it.

Just went it seems like the car doing well, Ping of dealth. Shakes again..Maybe fuel... High octane. dies on the freeway.

MAF get replaced. 

WOW It's just like when it was new. The power is back. But what is that little noise? Shocks are gone.

New Shocks.

Brake now making noise. Normal wear
New Tires.
New Rotor/Brake pads

So Smooth now.

Died on the road. 
New Battery

Morning crank, new noise. In a week, click click
New Starter.
Oil change. 
Found front Engine mount is bad.
New Engine Mount.
Radiator leaks
New Radiator

What another noise?
Idler Pulley probably. This weekend. 
New Belt

My friend 98 Maxima with almost the same amount of miles, runs like new. He doesn't even believe in regular oil change. Can't even hear or feel the engine via the steering wheel. While mine with 3k oil change and practically new parts shakes and makes noises.

My car loves spending time at the shop. The mechanics love my car too.
:wtf:


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## Cattman (Jun 22, 2004)

nelsito65 said:


> It is one of the worst code to have its cause pinpointed. It looks like you have a California spec maxima, which have two pre-cats (front and rear) and a catalytic converter. Some people swear by just replacing the front pre-cat and be done. It is the one closest to the front of the vehicle. I've been living with that code for the last 14 months that I've owned my present maxima (I had a 98 before this one). I replaced the bank 2 sensor 2 and it didn't do the trick. Some people recommend to at least trying a can of catalytic converter cleaner in a tank of gas, so I did, hoping for something to happen and it didn't do anything either. One of these days I'll bite the bullet and spend the $200 for the pre-cat and see if that gets rid of the code.



14 months with a bad front cat? Big mistake. At the first sign that a CA/NLEV precat has gone bad, its time to either replace the precat or remove it by installing a header/y-pipe system that eliminates both pre-cats. 

Almost certainly the ceramic substrate has begun breaking down by now, which means that fine sand is being sucked into the cylinders at the beginning of the piston downstroke before the exhaust valves have closed all the way. Sand in cylinders = scored cylinder walls and worn rings = increasing oil consumption = engine is toast, time to replace.

Brian C Catts
Cattman Performance


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## JNCoRacer (Apr 18, 2003)

Time for a Cattman exhaust. Mmmmmm, me want.


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