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P0420 Ford - Catalyst System Efficiency Below Threshold
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CrisGt Offline
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Sad P0420 Ford - Catalyst System Efficiency Below Threshold
Hi to all! I'm trying to work with mi efie on my ford explorer sportrack 2003, 4.0L, I changed all sensor for a new ones, the upstream works perfectly, the downstream I had troubles, with P0420,
I set 200mV and CEL on, P0420
I set 210mV and CEL on, P0420
I set 220mV and CEL on, P0420
..........
..........
I set 350mV and CEL on, P0420

So i decide to try with less than 200mV, i set 190....until 170mV and always P0420!!! in this values sometimes i can drive more than 200 miles and no CEL until 240 miles or some time i drove 40 miles and CEL on Sad

If don't use the efie for the downstream NO CEL on.

This i ssue is frustating for me, I don't know what I cand do!, I was thinking to set less than 150mV but I'm not sure if this could be work?.

I was thinking to remove the downstream from the efie, but I don't know if it's a good idea.

I tried with the oldest downstream sensor, and no CEL on, if set between 200mV and 350mV, but I know should be a new sensor but i was trying.

I hope can give me another ideas, thanks in advance.
07-05-2014 07:36 AM
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V8Billy Offline
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RE: P0420 Ford - Catalyst System Efficiency Below Threshold
I just installed a system on a 2007 Subaru and am getting a similar CEL. Running 200 mv on both sensors. Would love to get some feedback on this post also.
04-01-2015 12:58 PM
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carmenlizzy Offline
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RE: P0420 Ford - Catalyst System Efficiency Below Threshold
How can i get more info about it.?

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04-02-2015 03:44 AM
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Autotech Offline
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RE: P0420 Ford - Catalyst System Efficiency Below Threshold
The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor). A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase. When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.

As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

Possible causes - Three way catalyst converter Bank 1 - Exhaust tube - Intake air leaks - Fuel injectors may be faulty - Fuel injector leaks - Spark plugs may be faulty - Improper ignition timing - Engine Control Module (ECM)

Best way to save fuel is to stay home, but what fun would that be?
Auto Repair Manuals
07-16-2016 07:24 AM
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