>> >>
>>>(6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency...
>>> Fuel mileage doesn't seem too good, and am in process checking.
>>>The EGR valve diaphram doesn't move, so I suspect it needs replacing, the
>>>spark plugs have never been replaced as far as I know..., the tailpipe is
>>>black sooty, and the oxygen sensors may need replacing although there is >>>no
>>>code. I was wondering if replacing the plugs, EGR, and oxygen sensors >>>might
>>>prevent me from having to purchase new cats...?...
>>> Thanks
>>> R. >>
>>
>> I've heard that this code CAN be caused by bad O2 sensors. Certainly
>> cheaper to replace them than the cats. But that wouldn't cause a sooty
>> exhaust. You should replace the plugs anyways, especially if they are
>> old. They probably aren't that efficient any longer especially if they >> are original.
>>
>> Dan D
>> '99 Impreza 2.5 RS (son's)
>> Central NJ USA
>
> I agree with Dan. That is a lot of mileage and AT LEAST the front O2
> sensor must be getting lazy/bad if it is original. If the car has been
> running poorly for some time - the cat con COULD be compromised, but, as
> said, being the most expensive Item, I'd only do it after addressing the
> other issues.
>
> I THINK your car had platinum plugs from the factory(might be the H6es
> only get those?). That might explain them lasting this long. You COULD
> save a little and go with copper this time - but platinum or iridium would
> probably last until the wheels fall off and changing plugs on these
> vehicles can be a challenge. Certainly if I were paying a shop $80/hr -
> I'd put in the iridiums I think. If I were set up to do all my own
> wrenching and didn't mind the work - put the copper in.
>
> More people have fixed the 420 code with o2 sensors I think than with
> converters! OEM sensors seem to be much preferred. Check some on-line
> dealers to save a little money, or at least ask your local dealer to match
> on-line pricing. (I've had good luck with Jamie at
>
formatting link
>
> Carl
>
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