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p0420 code

15K views 4 replies 4 participants last post by  DALTON 
#1 ·
i got a check engine lite today the code was P0420 (M) 1/1 Catalytic Converter Efficiency Catalyst 1/1 efficiency below required level. anyone know what can cause this and how can i cure it thanks alot:drive::drive:
 
#2 ·
Taken from the Powertrain Diagnostic Manual.

Symptom List:
P0420-CATALYST 1/1 EFFICIENCY
P0430-CATALYST 2/1 EFFICIENCY

Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0420-CATALYST 1/1 EFFICIENCY.

When Monitored and Set Condition:

P0420-CATALYST 1/1 EFFICIENCY

When Monitored: After engine warm up to 70°C (158°F), 180 seconds of open throttle operation, at a speed greater than 18 mph and less than 55 mph, with the engine at 1200-1700 rpm and MAP vacuum between 15.0 and 21.0 inches of mercury (Hg).

Set Condition: As catalyst efficiency deteriorates, the switch rate of the downstream O2 sensor approaches that of the upstream O2 sensor. If at any point during the test the switch ratio reaches a predetermined value a counter is incremented by one.

P0430-CATALYST 2/1 EFFICIENCY

When Monitored: Engine running.
Set Condition: The Powertrain Control Module doesn’t recognize the Catalytic Converter warming up efficiently.

POSSIBLE CAUSES
GOOD TRIP EQUAL TO ZERO
VISUALLY INSPECT CATALYTIC CONVERTER
EXHAUST LEAK
ENGINE MECHANICAL CONDITION
AGING O2 SENSOR
CATALYTIC CONVERTER
 
#3 · (Edited)
Ya my 2000 4.7 (cali emissions) has the same code...
"Catalyst System Efficiency Below Threshold"
My scanner told me both of my pre-cat 02's were bad...
b1/s1 and b2/s1...I replaced them with pre-cat 02's from an 06 ram. (had them on a spare engine) This is when it gave me that "Catalyst System Efficiency Below Threshold" code. Coincidence? I don't know, I wouldn't think pre-cat 02's would cause that code. Post-cat 02's would.
My guess would be your post 02's are going, or your cat is going.
 
#4 ·
If the front O2s are changed out and the rear ones are old it will oftentimes trip the P0420/P0430 MIL code. Best practice is to change the rears when changing the fronts to keep them from reporting the MIL code (because they get lazy).
 
#5 · (Edited)
is there any reason to throw a panic and hit up the parts stores for a couple sensors with a p0420?? or is it the obd2 scanner tellin me i need more weed... 420 lol


here's my problem...

had to edit this because i had forgot to say i have no cats, somebody.... cough cough, cut them out and put piece of pipe in its place.. the sensors are still there of course...

I only ever got this error once... my truck used to be the check engine light nightmare, but i came to its rescue and this site quite a few times and managed to get her all fixed up right... thanks by the way!!! to everyone.

I havent seen a light in weeks which I was very happy....

I Bought this off somebody who claimed to be a mechanic, and it was the worst tooken' care of vehicle I have ever seen..... but thank good i love my truck and I changed some diapers!!!

Its a sharp lookin truck in my opinion, and now it is finally time for somebody work... I was trying to iron out the wrinkles first....


Thanks in advance
 
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