OBD Code P0420 Help !!

Apr 20, 2005 Last reply: 21 years ago 3 Replies
J

I have a 1997 F150 4.6 L 4WD with ~272 k miles and I am getting a periodic Check Engine light with code P0420 set (Catalyst System efficiency below threshold, Bank-1). In addition, the engine sometimes practically stalls when decelerating to a stop (RPMs go down to ~200 then bounce around before settling ~600 RPM). I did the EGR and Idle Air Control (IAC) sensor checks described in the Haynes Repair Manual (EGR Voltage, IAC Voltage/Resistance measurements) and they were all within spec. Any ideas/help would be greatly appreciated.



Thanks,



GaryB



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E

Try this site for more information on your P code.

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With the mileage you report on your vehicle, it sounds like the catalytic converter is finally giving up the ghost. Usually get a new one at AutoZone or any other parts store. Of course like anything else, I recommend replacing both at once to prevent changes in back pressure to the motor causing more damage to the engine than is necessary.

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E

Here is the page specifically for your code.

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J

Thanks Edward. I've replaced 2 O2 sensors in the past (not sure if the one causing this fault was replaced, but I'm sure going to check on it). Truck runs great otherwise (I bought it new and dirve it ~100 miles round trip to/from work every day-mostly on I-95 (Virginia))!

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