# 2.5S pre-cat problems & engine replacement



## T-ROCK2000 (Jul 19, 2007)

Hello everyone, this is my first post here but I have been on nissanclub for a while. I have been doing a little research into the big precat issue with the 02/03 2.5S engines. My dealer has now informed me that indeed that is my problem. LISTEN UP! If your 2.5S has less than 80k on it, the exhaust is manufacturer warrantied, by law. Since my car falls within those parameters NISSAN IS COVERING ENGINE REPLACEMENT. I don't have a manufacturers extended warranty, I do have an extended warranty through a warranty company but the service manager told me that they weren't even contacting them because Nissan found the flaw and is fixing it. Maybe they are finally actually owning up to their defective exhaust systems on those model engines. I don't want to count my chickens yet because even though the new engine is there, I don't have the car yet but I'm thinking it has to do with the fact that I made the service manager aware that I researched this problem and I let him view tons of material that supports this issue. In fact, some of that material that I found was here in nissanforums. Thanks to all


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## Harper (Jul 24, 2007)

*I am thrilled to find you!!!*



T-ROCK2000 said:


> Hello everyone, this is my first post here but I have been on nissanclub for a while. I have been doing a little research into the big precat issue with the 02/03 2.5S engines. My dealer has now informed me that indeed that is my problem. LISTEN UP! If your 2.5S has less than 80k on it, the exhaust is manufacturer warrantied, by law. Since my car falls within those parameters NISSAN IS COVERING ENGINE REPLACEMENT. I don't have a manufacturers extended warranty, I do have an extended warranty through a warranty company but the service manager told me that they weren't even contacting them because Nissan found the flaw and is fixing it. Maybe they are finally actually owning up to their defective exhaust systems on those model engines. I don't want to count my chickens yet because even though the new engine is there, I don't have the car yet but I'm thinking it has to do with the fact that I made the service manager aware that I researched this problem and I let him view tons of material that supports this issue. In fact, some of that material that I found was here in nissanforums. Thanks to all


Hello! This sounds strange, but I'm thrilled to find that other people are having this exact same problem. I have been beside myself with worry over it. I am getting the runaround like crazy. Do you recommend going straight to the dealer to resolve? I've been dealing with an agent at Nissan North America, but getting nowhere. My agent says she's "working with the dealership." My challenge is that I'm around 88K and I bought my car at Carmax. What should I do now? My Carmax warranty won't touch it and they've referred me back to Nissan. But Nissan is saying they can't help b/c I didn't buy it there and I'm past the manuf warranty. What should I do now? Should I show up at the dealership with my evidence? Thanks for your help!


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## T-ROCK2000 (Jul 19, 2007)

Harper said:


> Hello! This sounds strange, but I'm thrilled to find that other people are having this exact same problem. I have been beside myself with worry over it. I am getting the runaround like crazy. Do you recommend going straight to the dealer to resolve? I've been dealing with an agent at Nissan North America, but getting nowhere. My agent says she's "working with the dealership." My challenge is that I'm around 88K and I bought my car at Carmax. What should I do now? My Carmax warranty won't touch it and they've referred me back to Nissan. But Nissan is saying they can't help b/c I didn't buy it there and I'm past the manuf warranty. What should I do now? Should I show up at the dealership with my evidence? Thanks for your help!



First I'd run your VIN with NNA and see if the pre-cat recall procedure was performed, if it was, find the number for the dealership that did it. Contact them and ask for the records and present that to NNA, dispute the fact that the recall work was done and the pre-cat still managed to ruin the engine. You may have a tougher fight being that the exhaust is over the 80k, but I've heard it can still be done....


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## fivetears (Jul 26, 2007)

At the risk of sounding like an idiot, what exactly is the "pre-cat" issue? 
Is there a forum link to more detailed info on this subject?

Thanks in advance.


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## T-ROCK2000 (Jul 19, 2007)

The pre-cat issue is this, I'm trying to quote it as best as I can, saw it in numerous TSB's. At excessive heat and certain driving conditions, the materials in the pre-catalyst can deteriorate and sand-like particles can be sucked back into the engine, scoring the cylinder walls. This will increase oil consumption and/or coolant consumption which in turn will lower overall engine compression. If the owner continues to drive the vehicle under these conditions, the engine will need to be replaced.


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## fivetears (Jul 26, 2007)

Appreciate the information. Is there a forum link for a solid preventative maintenance / modification fix? I recall reading a spot on a Header Install with a brief spill on possible Emission Testing failure issues associated with it. I'd rather put a good legal fix on my '03 2.5L 77K miles pre-cat, than traverse the roads you have experienced.

Thanks.


T-ROCK2000 said:


> The pre-cat issue is this, I'm trying to quote it as best as I can, saw it in numerous TSB's. At excessive heat and certain driving conditions, the materials in the pre-catalyst can deteriorate and sand-like particles can be sucked back into the engine, scoring the cylinder walls. This will increase oil consumption and/or coolant consumption which in turn will lower overall engine compression. If the owner continues to drive the vehicle under these conditions, the engine will need to be replaced.


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## T-ROCK2000 (Jul 19, 2007)

Take a look through this thread, there may be something in here about it. I'll see if I can find some other stuff...

Excessive Oil Consumption 2002 Altima SE - Nissanclub.com Nissan Enthusiast Forums


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## fivetears (Jul 26, 2007)

Thank-you.


T-ROCK2000 said:


> Take a look through this thread, there may be something in here about it. I'll see if I can find some other stuff...
> 
> Excessive Oil Consumption 2002 Altima SE - Nissanclub.com Nissan Enthusiast Forums


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## roadkill2_0 (Sep 5, 2007)

do the 2004 engines have the same problem?


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## 02SentraSER (Aug 19, 2008)

fivetears said:


> Appreciate the information. Is there a forum link for a solid preventative maintenance / modification fix? I recall reading a spot on a Header Install with a brief spill on possible Emission Testing failure issues associated with it. I'd rather put a good legal fix on my '03 2.5L 77K miles pre-cat, than traverse the roads you have experienced.
> 
> Thanks.


I'd ALSO like to hear of a modification or fix!! Nissan should redesign the exhaust system OR buy our cars back! I've heard of factory Nissan replacement pre-cats causing the same exact problem!


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## dafamousext (May 11, 2007)

well i had the same problems. fixed the headers and still nothing. i had to replace the engine at my expsne. any way nissan can either reimburse me or do something ? after all, there rep has gone down and i will never buy a nissan.


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## wickchucker (Sep 30, 2008)

Hello. Do you have an update on this free repair? I am having the same issue with my 03 Altima - Dealer is not willing to replace ithe engine for free. Can you explain a bit more about what you had to do, say, demonstrate in order to get it replaced? I bought my car new. It now has 72,000, and I want to be able to convince the dealer and/or NNA to replace the engine for free beucase the Cat system is covered for 80K miles under federal law. 

Research time for me! Any advise input you could offer would be awesome. 





T-ROCK2000 said:


> Hello everyone, this is my first post here but I have been on nissanclub for a while. I have been doing a little research into the big precat issue with the 02/03 2.5S engines. My dealer has now informed me that indeed that is my problem. LISTEN UP! If your 2.5S has less than 80k on it, the exhaust is manufacturer warrantied, by law. Since my car falls within those parameters NISSAN IS COVERING ENGINE REPLACEMENT. I don't have a manufacturers extended warranty, I do have an extended warranty through a warranty company but the service manager told me that they weren't even contacting them because Nissan found the flaw and is fixing it. Maybe they are finally actually owning up to their defective exhaust systems on those model engines. I don't want to count my chickens yet because even though the new engine is there, I don't have the car yet but I'm thinking it has to do with the fact that I made the service manager aware that I researched this problem and I let him view tons of material that supports this issue. In fact, some of that material that I found was here in nissanforums. Thanks to all


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## bcgonzal15 (Mar 4, 2011)

*Nissan Altima 2.5 giving me hell 144k*

:wtf: I have (not knowing about the existing pre catalytic converter issues/recall) replaced the catalytic converters and now replaced the engine. I had an engine which belonged to a 2005 Nissan Altima with 50,000 miles put in. Now it still stating that it needs new catalytic converter again. The car is acting the same way it did before i'm way past the 80k and past the 100k. For those of you who have had luck after replacing the engine and catalytic converter, i would like to know if the solution lasted very long. I have poured all my money into this car and cannot keep pouring it in. 

Please help:waving:. Any advise will be appreciated. 

thanks, 
Bianca


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## paul79 (Sep 14, 2010)

Bianca: I'm in the same boat (except mine is a 2003 Altima). From all that I've read, all the Altima and Sentra cars that have the QR25DE engine in it will eventually have this issue. I'm not a mechanic, I don't understand the whole reason behind it. However, I am currently working with the NHTSA on the issue (since Nissan's recall procedure didn't resolve the issue), and I would recommend that IF you replace the engine, it appears to be highly recommended to forego (get rid of) the precat, either by gutting it (completely getting rid of the honeycomb structure inside) or swap it out with a different header.

At NHTSA, contact: [email protected] or [email protected] and let them know your situation. The more the better!


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## jimsem (Apr 19, 2011)

I have a question regarding this issue of pre-catalyst entering the engine and causing damage to cylinder walls, thus high oil consumption, thus engine burn-out, etc.

Seeing as the pre-cat is located on the exhaust side of the engine and exhaust normally flows outwards - how do particals from a pre-cat which has exhaust gas flow out and away from an engine enter into the cylinders, etc. Is there some secret way that exhaust re-enters the engine to cause such damage??? OR is there some other problem where dirt is entering the engine - such as poor seals along the air intake thereby allowing dirty air to enter via the intake side of the engine??? Just wondering - anyone with an answer - please


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## smj999smj (Jan 1, 2006)

jimsem said:


> I have a question regarding this issue of pre-catalyst entering the engine and causing damage to cylinder walls, thus high oil consumption, thus engine burn-out, etc.
> 
> Seeing as the pre-cat is located on the exhaust side of the engine and exhaust normally flows outwards - how do particals from a pre-cat which has exhaust gas flow out and away from an engine enter into the cylinders, etc. Is there some secret way that exhaust re-enters the engine to cause such damage??? OR is there some other problem where dirt is entering the engine - such as poor seals along the air intake thereby allowing dirty air to enter via the intake side of the engine??? Just wondering - anyone with an answer - please


The QR25DE's do not have a conventional EGR system. Rather than use an EGR valve to vent exhaust gas into the intake manifold, like most vehicles, it accomplishes it through the variable camshaft timing, pulling the exhaust gas back through the exhaust valve into the combustion chamber by partially opening the exhaust valve on the intake stroke of the piston.


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## bword (Dec 10, 2010)

Mark another 2002 2.5 that fell victim to the pre cat. I just bought my altima with 108k from a used car lot a few days ago. I couldnt help but noticed the horrendous noise it would make when cold starting and then eventually a CEL came on. I brought it to the dealership and the tech scanned it said there was a misfire on cylinder number 4 and that my motor was done thanks to the pre cat. I dont think the tech is BSing me, but the car does run decent after warming up. Im not sure what to do....


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## smj999smj (Jan 1, 2006)

I would talk to the used car dealer ASAP and see what they'll do for you. Always get an independant shop or dealer to check over a used car for you before you buy it. I also recommend get some sort of warranty if possible, even if it's only 6 months/6000 miles, that'll cover powertrain and drivetrain at least!


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## bword (Dec 10, 2010)

smj999smj said:


> I would talk to the used car dealer ASAP and see what they'll do for you. Always get an independant shop or dealer to check over a used car for you before you buy it. I also recommend get some sort of warranty if possible, even if it's only 6 months/6000 miles, that'll cover powertrain and drivetrain at least!


I called up the used car dealer which IMO is a pretty decent guy. He told me bring up the car monday mourning and were gonna drive it to his mechanic which im sure will end up leaning towards nothing wrong . Im planning on going back to the Nissan dealer before meeting this guy and getting a actual quote for the issue's which will cost me a cool 100 bucks :lame:. The reason I think im going to get shafted in this matter is because 

1. The sputtering and noise goes away after a few seconds of running when cold. 
2. It seems to run decent overall but I would say it feels like its lacking power maybe due a bum cylinder. 

Its not a consistent noise....yet. So worst case scenario nissan wont consider it a recall issue with the cats and this guy wont do anything to help me and ill have to keep driving it until it blows up. Im praying that the dealer might just give me a different car of equal value. I am so bummed out about this


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## bword (Dec 10, 2010)

Hey guys update time...

After bringing it back to the guy a few times and the motor blowing up on the highway. They put in a another motor ive been trying to figure out what year the replacement motor is but thats another story. Either way it runs a million times better and im debating on keeping it. I have a CEL for a 02/cat I cant remember which one it is but im thinking about changing the cat regardless. Would you guys say if the car is running great and you change the cat as a precaution id be okay for a few years? My wife loves this car but we fear of this thing blowing up again.


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