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Guest Message by DevFuse
 

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Code P0304


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5 replies to this topic

#1 JBRIII

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Posted 24 October 2003 - 05:20 PM

My wife's 96 Outback threw code P0304 (Cylinder #4 Misfire) last night after sitting at the airport for 2 days. The light went off by itself today. I ran the code when I got home this afternoon. It has also been throwing code P0420 (Catalyst below efficiency) about once every 4 weeks also after sitting for extended periods.

Is this anything to be overly concerned about?

Thanks,

John

#2 leaksoilknocksclutch

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Posted 24 October 2003 - 05:47 PM

The cylinder misfire code could be as simple as moisture in the gas - if it reoccurs, more diagnosis is required. The catalyst below eff. code could be the oxy sensor after the cat converter (there is 2 on your car - 1 b4 the cat and 1 after). How many miles on the car and have the oxy sensor(s) ever been replaced?

#3 JBRIII

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Posted 24 October 2003 - 06:14 PM

The car has 110K and to the best of my knowledge has never had the O2 sensors replaced. She bought the car in 98 with 67k

#4 leaksoilknocksclutch

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Posted 25 October 2003 - 08:09 AM

I would start with replacing the oxy sensor after (downstream from) the cat and clear the codes. Drive as usual and see if any more codes pop up.

#5 color-blind

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Posted 28 October 2003 - 01:17 PM

Ignore the converter code for now. First you need to determine the misfire code. I would suspect plug wires or a failing valve/guide. It is easiest and cheapest to simply replace #4 plug wire. If you have access to a leak-down tester you should check #4 cylinder.

As far as the converter is concerned it is common for failure. Yet you have more pressing concerns with the mis-fire.

#6 JBRIII

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Posted 28 October 2003 - 02:11 PM

Ordered some new wires and plugs. So far the code has not re-emerged. I put in a bottle of fuel system cleaner as well. I'll swap out and see what happens. Car seems strong, so it may have been an anomoly.

Thanks for all the input.

John




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