Have set this code two times in about 500 miles.
I have a code scanner for obd-II and cleared the code, then
my son drove the car, and about 3 weeks and 500 miles have brought
the code back. The hand scanner says code 420 has something to do with the catalytic converter being below minnium threshold performance.Does this mean the converter needs to be replaced or is there a possible problem with the last o2 sensor? How can I test for the right fix? If the converter is bad how much do they cost.
The truck has 124000 miles on it.

 

>H

ave set this code two times
>in about 500 miles.
>I have a code scanner for
>obd-II and cleared the code,
>then
>my son drove the car, and
>about 3 weeks and 500
>miles have brought
>the code back. The hand scanner
>says code 420 has something
>to do with the catalytic
>converter being below minnium threshold
>performance.Does this mean the converter
>needs to be replaced or
>is there a possible problem
>with the last o2 sensor?
>How can I test for
>the right fix? If the
>converter is bad how much
>do they cost.
>The truck has 124000 miles on
>it.


Are you getting any other codes ? Have any of the O2 Sensors been replaced ? Dont condem the converter simply because the code mentions it . The O2 sensor behind the converter is likely telling you something upstream is causing the problem . W/o the diagnostic routines & pinpoint tests its hard to make a diagnosis with any certainty .

 

No other codes set.
Truck has original sensors as far as I know.
Good driveability.
Have only owned vehicle for 6 weeks, but am sure of it's history as having had a good home and solid maintenance routine as far as lube and filters go.
Has 15 to 16 mpg milage.
Seems it may have a very very minor irregular idle speed.
Am using gasohol as it is only fuel available in Mn.

 

[font size="1" color="#FF0000"]LAST EDITED ON 04-Jun-01 AT 11:22 AM (EST)[/font][p]I'm having similar issues w/ my '96 Explorer. I also live in MN, hope it's not a fuel problem as the truck was originally a GA vehicle.

My "Check Engine" light has been illuminated for some time now and I thought they de-coded it as 402, it may have been 420 however. They said it was the RGC valve. I did have a Ford dealer replace the O2 sensor last February (shouldn't they have replaced the valve at that time, too?) when this issue started. The light came back on a short time later.

I also have noticed a little "wet" exhaust coming from tailpipe when I idle in one spot for a minute or two. Any one help? Thanks.

 

Sorry, NOT RGC, it's the EGR valve, sometimes my mind wanders. RGC is a term I use at work. that's what I get for surfing on company time. Again, any guidance appreciated. Thanks.

 

CATALYST MONITOR AND EXHAUST SYSTEM PINPOINT TEST HF

General Information

Pinpoint Test HF is used to diagnose the following items:
· Exhaust System pipes (both front & rear)
· Catalytic converter
· Exhaust system muffler
· Exhaust system tailpipe assembly
· Exhaust manifold
· Wiring harness circuits to both cylinder Bank 1 and Bank 2 downstream Heated Oxygen sensor(s)

Code Descriptions

DTC P0420 / 421 – Cylinder Bank 1 catalyst efficiency below acceptable threshold.

DTC P0430 / 431 - Cylinder Bank 2 catalyst efficiency below acceptable threshold.

NOTICE

Prior to starting this test procedure, verify that the customer has not refueled the vehicle with leaded gasoline or experience high engine oil consumption.

NOTICE

Complete the spark timing check portion of the Quick Test prior to proceeding with this repair chart as the spark timing may be retarded below the normal setting. If it is, exhaust gas temperatures may increase which could decrease the efficiency of the catalysts.


FLOW CHART DOWNLOADED IN MS WORD

Doug

 

I recently had a code 420. I looked in my Haynes manual and it did not offer much help. I reset the code and it has not reappeared. By the way, my 1996 Ford Explorer XLT has a V6 and 108,000 miles. Were you able to further diagnose and remedy your code 420?

 

I have a 96 XLT 4x4 with 110,000 miles and had the same problem - I would reset and the code would return not too long after - A friend of mine suggested replacing the plugs & wires and I did - I havn't had the code return yet (knock on wood) for almost 9 months now.