Truck (details in sig) threw a 430 code the other day. The generic meaning is "Catalyst Efficiency Below Threshold - Bank 2." The truck has 90,000 miles so I'm probably due for O2 sensors anyway, but do you think that might be the problem or is it probably time for a new cat? Truck runs great, can't notice any lack of power or anything. I tried to monitor the bank 2 rear O2 sensor on my scangauge but I'm not sure what the numbers mean, seemed like it would jump by about 50 (what units??), at idle from 1-10 up to 50 or 60 and at speed from 10-20 to 60 or 70. Since the reading jumps I'm thinking maybe that means the sensor is good? Is there a way to test the cat?

I had the #6 injector replaced about 6 months ago (under the 2005 ext. injector warranty) which was causing a lean code and miss. Is it possible the injector was stuck open and fouled the cat? In which case what's the likelihood of Ford picking up the tab?

 

If it were mine, I would:

1) Disconnect and re-connect the after cat O2 sensor and inspect wiring. Reset CEL. An intermittent or slightly dirty contact could be the root cause.

2) If it lights again, change all O2 sensors.

3) If it lights again, then consider changing the cat.

That is based on my experience of what the most likely culprits are on a vehicle with only 90K miles. It is just convenient for you that the cost of each is inversely proportional to the likelihood!

 

1) yes
2) no!
3) maybe

Yes and ....good question. If the converter was flooded with fuel, it's a VERY good chance that is the cause of the current indicated failure of the cat. I'd certainly press your local dealer, and if necessary, the zone office to follow up on this strong possibility.

 

Yes, just my luck! The first one is certainly cheap and easy enough so I'll give that a try tomorrow and see where it goes from there.

If step one doesn't work I'll go in and talk to the dealer. I had to push fairly hard to get them to honor the injector warranty and that was a known issue w/ a Ford issued extended warranty so I'm not holding my breath on that. If I don't get results there I'll go up the food chain. Is it possible to test the cat first to see if it's actually bad?

 

I did this to confirm my 99 cat was not holding me back, should work for you:

Pull out the front O2 sensor on side you feel is suspect. Get a fitting with the same thread as the o2 sensor (I forget what it was) one side - small barbed nipple other side, screw it in the O2 bung, and run a 10' section of small tubing from the barbed fitting to a vacuum gauge in the cab...go for a ride and run it up. If you have more then 2-3lbs of back pressure the cat is restricted.

You could always compare the back pressure reading to the other side if its a close call.

Cheers!

 

A P0430 code is not caused by a restricted cat, it's cause by a cat that is not properly storing oxygen. Testing the back pressure won't reveal the performance/functional condition of the cat. It would be useful for testing for a restricted exhaust that is affecting the ability of the engine to "breathe" which, in turns, can greatly effect engine power and performance.

Yes, but it takes a bit of testing equipment that isn't all that common at the DIYer level. I use a PC-based OBDII interface/software package that allows me to graphically display the upstream vs. downstream O2 sensor outputs. A properly working system will show the upstream sensor switching rapidly in response to the mixture control and a downstream sensor that switches very slowly. A bad cat will show a downstream sensor output that more closely tracks the upstream sensor output. In electronic terms, the cat acts like an integrator for the switched input signal.

For more details on how the sensors are supposed to work, consult the Ford OBDII Theory and Operations Manual, available for free download at www.motorcraftservice.com

 

I stand corrected that my quick test was for a restricted cat / exhaust. This is what happens when cats fail from my experience, as they wouldn't loose their designed capabilities absent this accompanying restriction...or a noticeable rattle.

It most likely not the cat at all, but just the front O2 sensors in need of replacement. mws250 pointed you in the right direction.

NC

 

I think my Scangauge II can track the outputs, just can't graph them. I was just checking the back one before and it was switching pretty fast, so that doesn't sound very good. I'll check the front one this weekend and see how they compare. Can you tell from the readings if the O2 sensor itself is good?

What software are you using? Do you know if Auto Enginuity has this feature? I've been looking at that but there's too many other things the truck needs first, maybe I should just bite the bullet.

 

Want to bet on that? Sounds like your experience is limited to failures of the catalyst's physical structure, not its operational integrity. I've seen both plenty of times - sometimes separately, sometimes together.

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I use Alex Peper's OBDII interface and software. I've had it for around 10 years or so. I've never used the Auto Enginuity package so I'm not familiar with its capabilities.

The functionality of the sensors, both upstream and downstream, was tested by the PCM prior to execution of the catalyst efficiency monitor. It's tough (but not impossible) to get past those tests with a defective O2 sensor.

Keep in mind that the cats were covered under the federal 8/80 emissions warranty. While you're a bit over the mileage, a strong case can be made that there is a direct causal link between the previous injector failure and the current catalytic converter failure. If you have an ongoing relationship with your local Ford dealer, they may be able to help with getting Ford to step up.

If not or it you don't have any luck getting coverage on the cat, you do have several options.

1) If you don't have emissions testing and don't care about emissions, ignore the fault.
2) If you have emissions testing but don't care about the emissions, install one of the possible "cheats" to fool the PCM. MIL eliminators and anti-foulers come to mind. You may have to gut the cat if the substrate fails mechanically.
3) Replace it at your own expense. Investigate aftermarket parts for savings.


Good luck!