p0420 Catalyst Efficiency Below Threshold (Bank 1)

[gavnator]

Does anyone know if this code is actually related to the catalytic cover itself or has to do with faulty sensors. The reason I ask is that for over 2 years I've received the "service engine soon" light intermittently 2 or 3 times a year. I reset the code and the code stays off for 4 months at a time. Now it comes on within a shorter period. Sept 2017 I ran a P0430 Bank 2 code and took the M to Infiniti. They said the 3 way cat assembly needed replacing. Cost $1200 in 2017. If it is the cat is this something a good repair shop can do or do I go to Infiniti to replace it assuming the catalytic converter is bad. 06' M35X with 110,000 on the clock. Any possibly this is sensor related and not the cat. Thanks for your help.

[VStar650CL]

When occurring by themselves, P0420/P0430 are strictly "dead cat" codes which won't be caused by a bad sensor. The only other thing that can cause them is an exhaust leak in the vicinity of the rear sensor, but we see that very infrequently. In this case, your cat is progressively getting weaker which is why the ECM is flagging it more frequently. There's nothing wrong with going aftermarket on the cat to keep the cost down, but don't go bargain basement, stick with a reputable brand like Bosal, AP/Eastern, Walker, Davico, etc. Pretty much anything you find in RockAuto will be reputable, China-cheap is what you want to avoid. The job itself isn't rocket science but it isn't easy either. A good general repair shop should have no issues with it, but most will quote additional labor time to account for rust and corrosion on an older vehicle. In this case, Motor quotes 1.1 hours for either side but most places will probably upcharge to 1.5~2.0.

[gavnator]

VStar, thanks for the quick response. Your reply pretty much sums up my thinking. I’ve got a local tech that can handle it. This is the only Nissan product I’ve ever owned where I’ve had to replace catalytic converters. Pathfinders, Maxima’s nothing.

[Larz]

My cats went titz-up at about 10ok miles. BOTH cats! I ordered them from Infinitipartsonline and paid the deale to install them. I know I made a thread about it, but search isn't working at the moment. I'll try again later and attach it here. I t included ordering, return of old cats, and all the pricing.

UPDATE: Turns out search DOES work (if you do it right,LOL)

post6771650.html?hilit=catalytic#p6771650

[VStar650CL]

Predicting cat longevity is a bit like rear wheel bearings, some go 100K and die while others outlive the vehicle. For cats, they practically all reach 100K and I'd say 160K is a good average, but some get well past 200K. Certain factors like driving with intermittent misfires will definitely shorten their lives, but for the most part, if anyone knows what makes one outlive another on equally well-maintained vehicles, I'd love to hear the answer.

[gavnator]

VStar, help me out with the term "intermittent misfires" . How does this occur? Never heard the term in relationship to these motors. This M35X is serviced for all intervals long before their due. The Bank 2 cat craped out at 84,500. That was in 2017. Bank 1 cat went at 110,400. I use nothing but top tier 93 octane always. This car does not misfire. Please expand on this topic. Tkx.

[VStar650CL]

Misfires that happen under the radar are usually from one of two things, carbon or poor grounding. If you don't drive like grandma then carbon isn't usually an issue, but if you baby the car then adding a de-carboning to your maintenance routine may help. Carbon also directly affects the efficiency of the cats, not just indirectly by way of affecting the engine's efficiency. Poor grounds are of course easy to check for with voltage drop, but they're often neglected and the first thing they affect is the efficiency of the FET's in the spark coils. Naturally, it's also possible that your cats were just built on a Friday.

[EniGmA1987]

If your engine is running rich it will also kill the cats faster by not burning all the fuel. That fuel gets pushed down your tailpipes and will coat the catalyst in the cats (the platinum honeycomb thing). As the exhaust temps rise it can/will combust unburned fuel and cause great harm to the catalytic converters.

[gavnator]

Took it in this week and sure enough the cat was bad. Had it replaced and all is good. Thanks to all for your help.