PO430, Catalyst Efficiency Below Threshold? What to do?
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Senior Member
Joined: Apr 2000
Posts: 1,823
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From: Hollywood, CA
PO430, Catalyst Efficiency Below Threshold? What to do?
Well, I got the misfire fixed (evidently bad coil packs three times in a row, but now I have good fire), and after about 75 miles I got a new engine code, now I have an engine code that says PO430, Catalyst Efficiency Below Threshold. What fixes this?
Technical Article Contributor
Joined: Jun 2002
Posts: 10,511
Likes: 10
From: Under the flightpath of old ORD 22R
Only 1 other post on a P0430 DTC.
https://www.f150online.com/forums/sh...threadid=51407
As fro what fixes it, good question, that post was some what open ended, and I did not see a real soultion posted.
Here is what is in the service manual on it, Sorry I can't add to it myself, I have no clue what else to say on the topic.
DTC
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
Description
Indicates Bank 2 catalyst system efficiency is below the acceptable threshold.
Possible Causes
Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler /tailpipe assembly
Retarded spark timing
Diagnostic Aides
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
Good luck, and post back what you find fixes it for the next member.
https://www.f150online.com/forums/sh...threadid=51407
As fro what fixes it, good question, that post was some what open ended, and I did not see a real soultion posted.
Here is what is in the service manual on it, Sorry I can't add to it myself, I have no clue what else to say on the topic.
DTC
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
Description
Indicates Bank 2 catalyst system efficiency is below the acceptable threshold.
Possible Causes
Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler /tailpipe assembly
Retarded spark timing
Diagnostic Aides
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
Good luck, and post back what you find fixes it for the next member.
Junior Member
Joined: Oct 2009
Posts: 1
Likes: 0
Code P0430 Catalyst Effiency Below Threshold (Bank 2)
- Just curious if you figured out what the problem was with your vehicle? I have a 2003 Ford Expeditiona dn replaced the coils last weekend and now I received the code P0430, Catalyst Effiency Below Threshold (Bank 2)
So, if you can provide some information I would appreciate that.
Thank you.
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Why did you replace the coils Nick? If it was misfiring, -raw fuel may have smoked your converters. Your O2 is good, so it's not that. Check the rear converter under the heat shield. when they implode from a misfire problem, they will usually crack along the bottom under the shield, from right to left.
