Cheapest cat to cure code PO421

[crossy]

Hey guys i have a 99 Protege i use to commute in and drive to school, The check engine light is on and i scanned it with my MAC tools OTC scanner and got PO421 for bad Pre-cat from what i've read. (the one coming off the manifold) . It won't pass inspection with the light on, i reset the light but it comes back on.

I found this cat and it looks like a good deal. http://www.drivewire.com/vehicle/maz...tic-converter/

I'm looking for a replacement cat for it thats not $300. LOL

If anyone has any experience with this cat, or this company. let me know. I'll be doing the work myself on a lift most likely.

Thanks
Brandon

[goldstar]

Before you replace the front cat, check the condition of the O2 sensors. According to the FSM, P0421 (Warm-up catalyst system efficiency below threshold) may be caused by:
1. Deterioration or malfunction of the front cat
2. Exhaust gas leakage
3. Looseness of front O2 sensor
4. Looseness of rear O2 sensor
5. Front O2 sensor malfunction

If you're lucky, it'll be one of the O2 sensors rather than the cat.

Happy Motoring!

[yunvmyegt]

check the egr passages .....

[Beerizfood]

Not big on bosal myself but i cannot say if they are any good cat-wise.
421 is the monitored pre-cat and unless you have a cracked manifold or you are over fueling then its most likely the cat.
If your Mac scanner will monitor o2 voltages ,look at the front and rear o2,s.
The front should switch back and fourth and the rear should remain fairly constant.
You may allready know this and condemed the cat .
I also will remove the upper (front) o2 and take a peek at the top surface,if its cracked,plugged,broken ,eaten away i would say its toast.
If however you have another fuel issue like a stuck regulator and its dumping fuel then the cat cannot "clean out" and become saturated but still may be ok.
On the other hand (lol) if you have a lean condition say a vacuum leak ,the cars logic will dump fuel as a protection to compensate for the lean reading.Monitoring your short and long fuel trims will give evidence to this.
any other codes??? or data???

[Brahman]

Could I check these same items on my mom's 1998 Protege LX 4 Cyl 1.5L (<191,000 miles)? Her car is exhibiting similar symptoms such as CEL constantly on, poor performance issues, etc. When I used a simple OBD2 code reader I received a P0400 and P0421 code. As I had read on another post the P0400 code could be solved by either cleaning or replacing the EGR valve--could this be a problem with the sensor as well? The other interesting (or disgusting) thing that is occurring is that after taking the car on even short trips there is a very horrendous smell coming up from the engine which dissipates about 5 minutes or so after the engine is shut off. Could this be more of a problem with the catalytic converter than the sensor? After looking at the exhaust manifold I can see no evidence of cracks or holes--perhaps a gasket replacement is in order? There is something else that's happening and I'm not sure if it's normal or not: after checking out the car I noticed that the engine idle speed was set way too high, something like 1300 RPMs. But after lowering the idle speed down to around 700 RPMs I've noticed that the engine has a very high pitched sound to it and runs about 3000 RPMs when freeway driving (55 to 75 mph). Could these all be symptoms of the same problem?

[irishkev90]

Yes, you could.

[Nutbag01]

How do I check the O2 sensor???

[Nutbag01]

I also have a sweet smell about 2-3 minutes after starting my car,but it only lasts for maybe 30 seconds.Guess it smells like antifreeze.My car has no power problems,also runs about 3000rpm at 65mph but thought it was just a high rpm motor,true?
The P0421 popped up about 3hrs after I bought the car(I'm guessing they knew about it and disconnected battery the night before).How do I put in a straight pipe and bypass the O2 sensor?

[Nutbag01]

P.S It gets on average 34mpg and doesn't lose any fluid from radiator.

[crazycanadian]

I am not going to get into all the details of diagnosing either a PO421 or a P0400.. It takes some time/skill and understanding of systems to be able to use a scanner accurately to diagnose this problem properly...

Cheap and cat converter don't go hand in hand when it comes to fixing this code... the PCM is programmed to look for very specific voltages do with the rear O2 sensor... Cheap converters often will solve the problem for 6 months maybe a year... But never last long.. and thats if you get lucky and it does turn the light out...

The best aftermarket cats that will solve the issue and not have the light come back on are California spec emissions cats...

P0421 codes wont harm how the motor runs FYI...