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infamous p0420

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2004 RAV4

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Discussion starter · #1 ·
Hello

Im new to this forum and I have been searching all over for the right answer to this problem. I have a 2004 Rav4 with a 4cyl 105,000 miles. A couple of weeks ago I got this code, looked on this forum and seen that the MAF sensor need cleaned. I cleaned the sensor and about 300 miles later the code came back. So I bought a new MAF sensor hoping this would fix the problem....it didnt about 200 miles later it came back. I see that on the earlier models they say the ECM needs reprogrammed but not on the 04. So should I change the downstream sensor?? Sorry this is a long post, but I just want to try and resovle this problem.

Thanks
 
#2 ·
I don't worry about it anymore. We've had the 0420 and 0430 pop up for 7 YEARS now on our 2002. We did the ECU reprogram at the dealer and that didn't do squat. I didn't want to drop $1000 on a new cat, so I used this little $20 gem (now discontinued) that I've had for a long time to clear the codes.

Image


It'll still throw a code every now and again, but we don't even worry about it unless it's time for the annual inspection. If it comes up before the inspection, I clear it and drive around for a week before getting it inspected. Otherwise it'll fail. IMHO, you don't need to worry about it. Just clear it and move on.
 
#3 ·
How many miles on that 2004? Do you have problems with oil consumption? Have you had any problems with misfiring, lower gas mpg, anything else that might be relevent? P0420 is catalyst below efficiency, meaning that you have a problem with your catalytic converter or A/F sensor or downstream O2 sensor. Mechanical problems with the converter are almost always due to a prior or concurrent engine problem. But they are dirt cheap, probably cheaper than what you paid for that new MAF sensor. Walker, Eastern make bolt-right-up cats for less than $200 for the 2.4L.
 
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#4 ·
The O2 sensor went a couple off times in my rav4.2 replace one. in the end i parked the car in a river for a few minutes to wash the underside of the car,(kept doing every few months) as i didn't know the exact location of the sensor, just new it was underneath. never had a problem after that.... maybe it was a glitch? maybe washing the sensor kept it from developing a further fault.
 
Discussion starter · #5 ·
It's got 105,000 on it. The new MAF was $90, so it's cheaper than a cat. The Rav has never used oil since I have had it and I am getting the same mpg as I was months before this problem. I just want to get it fixed cause I'm tired of having the light come on.
 
#6 ·
Do the cat next then, since a direct fit bolt-in replacement is not too hard. PB Blast the O2 sensors and all nuts the night before.
 
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Discussion starter · #7 ·
I would think if the cat was bad the car would run bad, but it runs fine. I priced the o2 sensor (down) an it's $100. Just thought there would be a definite answer to fix this code. I did read on the 01-03 that some people took their car to the dealership and they replaced the MAF, both sensors and the cat for the tune of about $1500-2000. I can do all the work so I will save the labor cost. Just want to know what everyone else is doing to fix this code.
 
#8 ·
The cat in 01-03 is different, a real beast of a thing, as it incorporates the exhaust manifold.

Cats + O2 sensors often get replaced together because a bad O2 sensor can ruin the cat. But a poisoned cat will not automatically make the engine run bad, it just means its ability to store and release oxygen has deteriorated too much.
 
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#9 ·
My '03 Rav4 threw P0420 and P0430 a couple of days after changing an ignition coil. The car runs good and gets exactly the same gas mileage as before. I bought an OBD2 scanner and it shows these codes along with P0420 P and P0430 P. I clear the codes and they return after 100 miles. Any idea what the last two codes with "P" following the code might mean?
 
Discussion starter · #10 ·
Talked to alot of people about this cat being bad. They are telling me what I thought that if the cat is bad the car won't run right. So I'm thinking the down sensor will be my next part I change. Rocknrider I have never seen a code with a P after it, it's usually just P____. Sorry I can't help ya
 
#11 ·
2004 RAV4 said:
Talked to alot of people about this cat being bad. They are telling me what I thought that if the cat is bad the car won't run right. So I'm thinking the down sensor will be my next part I change. Rocknrider I have never seen a code with a P after it, it's usually just P____. Sorry I can't help ya
Click to expand...
I think you are talking \\\\\\\\ listening to the wrong people. Unless the cat is clogged, it is not going to affect how the engine runs. It is an exhaust emissions control device.

I expect that you have a bad cat or a bad O2 sensor following the cat. The O2 sensor after the cat monitors the performance of the cat.
 
#12 ·
P prolly means pending.
 
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#14 ·
Let me be more specific: P0420 P prolly means Pending P0420
 
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#18 ·
What is the device you reference in the picture?

Master slacker said:
I don't worry about it anymore. We've had the 0420 and 0430 pop up for 7 YEARS now on our 2002. We did the ECU reprogram at the dealer and that didn't do squat. I didn't want to drop $1000 on a new cat, so I used this little $20 gem (now discontinued) that I've had for a long time to clear the codes.

Image


It'll still throw a code every now and again, but we don't even worry about it unless it's time for the annual inspection. If it comes up before the inspection, I clear it and drive around for a week before getting it inspected. Otherwise it'll fail. IMHO, you don't need to worry about it. Just clear it and move on.
Click to expand...
so I used this little $20 gem (now discontinued) that I've had for a long time to clear the codes<----what is it, what's it called, what does it do, where did you get it, is there something similar? Thanks
 
#19 ·
I had the same code P0420 show up on my 2004 Rav4. It was linked with another code that had a misfire in cylinder 4 and my husband changed the bad coil. Misfire code went away, P0420 came back later that night. Does he need to go ahead and change the cat converter or check the O2 sensors first?

Or change both the cat and O2 sensors?
 
#20 ·
You could do what my friend did. Spend a grand on a converter and O2 sensors then do this $10 fix
It got the 2003 Civic thru emissions for two more years and with 200,000 miles maybe it'll be replaced if it doesn't pass then.
 
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Dr. Dyno
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