maachine

got the code. can feel a slight delay in throttle response coming off idle. will get a new air cleaner tomorrow and will clean any sensors in the air intake tubes and what not. anything else to look at?

wyoming9

iTrader: (1)

Do you have any idea what this code is??

P0420 is Catalytic Converter is below the threshold for efficiency

Meaning the ECM is not seeing enough difference between the up stream and down stream sensors for what ever reason

Which means the Converters are not working like they should

The O2 or Air fuel sensor or the wiring or the ECM is at fault.

Not knowing just what your working on.

Check the rear sensor first you might get lucky .

maachine

i looked up the code before i posted this. i googled the fixes for it. actually the "clean your MAF" thread thats been on this site mentioned this code as well. i've known i needed a new air filter, just been neglecting it. which is a fix for this code. same thing with a dirty MAF sensor.

so i cleaned the MAF sensor today (which was really dirty, i cleaned it about 30,000 miles ago) and replaced the air filter. i reset the code and it hasnt come back yet. the delay off idle is gone and truck seems to have more power than before. so i'm thinking all is well. if it comes back, i'll update.

maachine

and thanks for the response wyoming9. you're one of the few guys that are consistent with help around here. its appreciated!

TheDurk

It can take a while, like a full tank of gas, for the cat test to complete and not fail. Until then, you have just reset your test markers. Only a scanner can tell you if the test is complete. If you can smell sulfur out your exhaust your cats are probably toast. If not, and your O2 sensors have 80k plus or you have no idea, it is probably worth swapping them before swapping cats. After all, anybody who swaps cats is going to put new ones in anyway.

Before anything else, check carefully for any exhaust leak between the rear sensor and the manifold. That is often the easy, cheap fix.

And please, it's P0420. The Po420 thing makes it tough for people searching, including you.

wyoming9

iTrader: (1)

I was going to say about the same thing

It can take quite a while for all the tests to run

75w90mantraN

I replaced both Air/Fuel and downstream oxygen sensors around 170k, but was impatient to wait for the CEL to go away on its own, so I reset the ECU, and it didn't come back. That was about 1 yr ago.

Oh, if you end up replacing the sensors, use OEM/Denso and pick the correct type for your vehicle. I got the wrong A/F one and had to buy another one for California-type emissions. Lucky all it was for you was simply replacing the air filter and cleaning the MAF.

On the subject of what else to do as far as that code, any maintenance would be prudent. Fuel filter, PCV valve, plugs, wires, coolant, timing belt... technically as good a tune-up you can do. And as previously mentioned, check for exhaust leaks. Lot of info on the net on various methods on how to check...and fix. I didn't find any leaks on mine when I had p0420 and recently, p0171.

Cat converters are expensive to replace (few thousand), so thank heaven that p0420 code exists - it's a precursor to cat failure. A good link that got me started back last yr...
http://www.obd-codes.com/p0420

Emissions testing is like taxes for some. In Cali, man, there's no escape.

maachine

for real. i hate california.

code just came back. i replaced one O2 sensor a few years ago. but it threw a code specifically for that when it went bad. spark plug wires and spark plugs have been changed recently. i got a misfire code on cyl. 6 and it was a bad spark plug wire.

i do need to swap out the timing belt and water pump (preventative maintenance) but the timing belt has been due for a while. i'm waiting to get my old dodge running right (rocker arm issue) then i'm going to do the timing belt and water pump on my yoter.

i'll check the pcv valve. uhh fuel filter was changed out about 3 or 4 years ago if i recall correctly. probably has about 50,000 miles on it now. every other time i change the oil, i throw a bottle of seafoam in the gas tank. in fact i just did that on this last tank of gas

maachine

and out of curiosity, is a visual check the only thing you can do to find out if the CAT is clogged?

i'm sure its the original catalytic converter. i've owned this truck since it had 68,000 miles and it has 160,000 on it now.

maachine

PCV valve is fine. it was functioning but blew it out with brake cleaner anyway.

maachine

ok so after doing a bunch of research and playing with my torque app. i've learned some stuff.

pics! you know what i'm about to do?

wyoming9

iTrader: (1)

Good luck I hope it works!!

maachine

seems to have worked out. no codes have been thrown and the DTC shows that all the system checks are complete. here in the next few days i'll probably take the cats off the exhaust system and drill a few holes in them. open the exhaust up a little bit.

only reason i did that mod was because i'm thinking my cats are bad. i dont have emission testing where i live so no point is spending 300$. especially after spending 250$ yesterday on a new windshield.

maachine

ok just to update, i gutted my cats after doing the O2 sensor bypass. rear sensor is throwing a P0136 code now. since the cats arent restricting flow like they were, there is too much exhaust gas going passed the sensor.

since i couldnt find a spacer for the sensor (or dont have the tools to make one) and the spark defouler trick wont work. thinking i might wrap the O2 sensor with stainless steel zip ties and see what happens.

hope this helps someone in the future.