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View Full Version : Help P0420!!!!

Caedmon7777
10-06-2005, 03:35 AM
My '00 DX is throwing the P0420 code on and off interrmittenly for a while I think it's the O2 sensor but the guy at Autozone said that it could be that the first piston might be misfiring. I have roughly 110,000 miles on it and about to change the belts on it. Do you think changing the belts will help or do I need to do the O2 sensor too? Help would be very much appriciated.
Witchdoktor
10-10-2005, 04:08 AM
P0420 (http://www.msprotege.com/forum/search.php?searchid=1456819)
Shane5425
10-10-2005, 07:37 AM
k, po420 = What?? cylinder 1 misfire or something/? we need more info..
Killer 8
10-10-2005, 09:23 AM
have you done anything to the 02 or you could just take it out and look at it cause it might just need to be replaced since you have so many miles on it. Also did they give you a print out on what the code is?
boostisgood
10-10-2005, 10:02 AM
DTC PO420- Catalyst efficiency below threshold.

Possible cause
Cat defective or deteriorated
Exhaust gas leak
Loosness of frt HO2s
Loosness of rear HO2s
HO2s FRT malfunction

This is from Alldata, I cant post the whole page on the code at work. Sorry.
boostisgood
10-10-2005, 10:05 AM
BTW, dont listen to the guy at autozone. They dont know shit, thats why they are autozone. If you had a misfire you woulda recieved a misfire code po301 for a #1 cyl miss 302 for #2 303 for #3 304 for #4 or 300 for a random.
Shane5425
10-10-2005, 11:00 AM
id say 2nd o2 sensor. seems to be most common
TampaSport20
10-10-2005, 11:47 AM
99-00 if its federal emissions (not california) only has one cat and one 02 sensor
boostisgood
10-10-2005, 12:21 PM
No, anything after 96 has 2 O2 sensors required by FEDERAL Emissions requirements.
Shane5425
10-10-2005, 02:33 PM
99-00 if its federal emissions (not california) only has one cat and one 02 sensor

we have 2.. trust me
solid_snake
10-10-2005, 02:39 PM
99-00 if its federal emissions (not california) only has one cat and one 02 sensor
2 sensors, i had a CEL with like 4 codes, and i replaced 2 HO2S when i had my protege
TampaSport20
10-10-2005, 03:46 PM
2 sensors, i had a CEL with like 4 codes, and i replaced 2 HO2S when i had my protege

Didnt you also try to inform me where the EGR valve is on my federal emissions 1.6L , which has no egr system
solid_snake
10-10-2005, 03:49 PM
Didnt you also try to inform me where the EGR valve is on my federal emissions 1.6L , which has no egr system
well, maybe i had a non-federal emissions in my car, but the california one, who knows... but it had only one cat (boom07)
sorry for any inconvenience
TampaSport20
10-10-2005, 03:51 PM
well, maybe i had a non-federal emissions in my car, but the california one, who knows.
sorry for any inconvenience

that means you have 2 cats and 2 sensors....

no inconvenience...just giving you a hard time...hard to convey in text (thumb)
TampaSport20
10-10-2005, 03:52 PM
we have 2.. trust me

lol, I dont trust you anymore with your sideways PRC valve
solid_snake
10-10-2005, 03:54 PM
that means you have 2 cats and 2 sensors....

no inconvenience...just giving you a hard time...hard to convey in text (thumb)
well maybe i was just aware of the 1st cat,
anyways, i replaced 2 HO2Ss, and the TPS, and the stupid CEL was still on...
yeah i disconnected the neg battery cable when i replaced them

but the tranny was starting to act up too (O/D light flashing)
oh well, i don't have that care anymore
Shane5425
10-10-2005, 04:30 PM
lol, I dont trust you anymore with your sideways PRC valve

lol, i had to make room for my begi rrfpr... lol
Caedmon7777
10-11-2005, 01:58 AM
lol, i had to make room for my begi rrfpr... lol
Well I think I need to change the Belts. I have been smelling a burning smell by the belts when I rev the engine. I think the belts are worn. I will change the O2 sensor but I think I will change the belts first. thanks for the help guys. By the way, how much does it cost to change the timing belt?