P0420 in association with P0302

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11-05-2007 | 10:48 PM

sirvroomsalot

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P0420 in association with P0302

For a while my car has had the P0420 code running, (pre converter O2 sensor) and only recently has my car started to run rough, and is sluggish off the get go, and only just recently the P0302 code flashed (cylinder #2 misfire) ive seen that it may be a array of things including plugs, wires and air filters to be of blame, i was just wondering of there is any corrolation between the two codes

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11-05-2007 | 10:53 PM

03neonRT

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From: Charleston, SC

RE: P0420 in association with P0302

Possible causes for a P0302 are:[*]Intermittent misfire[*]Ignition wire[*]ASD relay output circuit (coil)[*]Engine mechanical problem[*]Ignition coil[*]Coil control circuit[*]Spark plug[*]Checking fuel pressure[*]Fuel pump inlet strainer plugged[*]Restricted fuel supply line[*]Fuel pump module[*]Checking fuel leak down[*]Fuel injector operation[*]ASD relay output circuit (Injector)[*]Fuel injector[*]Injector control circuit[*]PCM (ignition system)[*]PCM

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11-05-2007 | 10:53 PM

Pharmboy

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RE: P0420 in association with P0302

the 302 can be caused by the 420 so get that first.
edit: i lie, the 420 is converter efficincy, you said pre cat o2 which is wrong, if it were a code for the pre cat o2, what i said would hold.

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11-05-2007 | 10:58 PM

Pharmboy

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RE: P0420 in association with P0302

Quote:

ORIGINAL: 03neonRT

Possible causes for a P0302 are:[*]Intermittent misfire[*]Ignition wire[*]ASD relay output circuit (coil)[*]Engine mechanical problem[*]Ignition coil[*]Coil control circuit[*]Spark plug[*]Checking fuel pressure[*]Fuel pump inlet strainer plugged[*]Restricted fuel supply line[*]Fuel pump module[*]Checking fuel leak down[*]Fuel injector operation[*]ASD relay output circuit (Injector)[*]Fuel injector[*]Injector control circuit[*]PCM (ignition system)[*]PCM

absotutely true, but if it's running a bit lean due to the 02 problem (likely), the problem is likely because of that. This does mean that your #2 cylinder is the weakest because the problem is showing there, and is probably due to one of the reasons above.
EDIT: I LIE AGAIN

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11-05-2007 | 11:07 PM

ewetho

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From: Kankakee, IL

RE: P0420 in association with P0302

At this point a basic tune-up (plugs and wires would probably be good anyway) and then troubleshoot the O2 code. Hopefully just an O2.

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11-05-2007 | 11:07 PM

sirvroomsalot

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RE: P0420 in association with P0302

well thats good to know, its going in to our garage tomorrow where the ebrake cable and the sound system rough-in will take place, i will definatly check into it

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