Hot Rod Farmer: Taking the mystery away from the catalytic converter.
March 10, 2021Podcast: Play in new window | Download (Duration: 1:01:41 — 98.8MB)
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Home » Hot Rod Farmer: Taking the mystery away from the catalytic converter.
Hello Ray
I have a question about my brothers 2011 Ford F150 with the V6 Eco Boost engine. He is about to put it up for sale but there is a check engine light on and the code it’s showing is for a plugged Catalytic Converter on the driver’s side and the dealer wants $550.00 to fix it.
It started when he had 40,000 miles on it, the code was erased and around 1,000 miles later it came back on. He says the performance and fuel millage hasn’t changed so he was thinking it might be a faulty sensor or bad wire connection someplace.
He has since put around 30,000 miles on it with no other problems.I would like to know your thoughts on this.
I know you just had a show on Taking the Mystery away from the Catalytic Converter, I’m wondering if the converter is coated inside, and if it is how did it happen?
I really enjoy your podcasts and listen to them all as well as the Farmer Minute.
Thank You and keep up the good work.
Gary
Hi Gary!
It is great to hear from you. Thanks for being such a faithful listener to my shows.
If I am reading your note correctly, the issue began at around 40,000 miles… the code(s) were erased and it took around 1,000 miles for it to reset (the truck would then have around 41,000 miles), and he has driven it that way (with the SES light on and the code stored) for 30,000 miles. Thus the truck now has around 70,000 miles. If this is correct I will offer the following thoughts.
You are correct, either the cat is coated internally or for some reason the monolith fractured and came apart, if the code indeed is valid. To the best of my knowledge there is not a code for a plugged cat (it would need two pressure transducers for that) but instead a flag for converter efficiency. I am confident that the truck has an efficiency code.
The system (all OBD-II use the same logic) determines cat efficiency by the output voltage of the second or post cat sensor. The primary O2 sensor is for fuel control (it is closest to the engine) while the sensor post cat determines conversion rate.
What I suggest is to erase the memory from the system and have your brother use the truck as he normally does. Let’s see if it sets. If it does, then if it is possible, switch the left and right bank post cat sensors. Sometimes you cannot do this due to the length of the wire on the sensor. I do NOT want you to switch the harness but instead, remove each sensor and switch locations. If the right bank now flags, you know it is the sensor. If not, it is the cat.
Since there is no drop in performance or fuel economy, at most the cat would be inefficient. Since the other bank’s cat did not drop in efficiency, I would tend to think that the monolith came apart inside for some reason. It would be very rare to coat only one cat on a V-shaped engine if it were fuel, etc. It is an EcoBoost so there is the possibility of some oil going past the turbo compressor seal on that bank. That would coat the cat and drop its efficiency.
I do not recall where you live… but…. and this is illegal, if they still sell them, there are OBD-II trickers. The guys that build hot rod engines use them with long tube headers. You unplug the cat’s O2 sensor and plug the tricker into the wiring harness. The ECU is looking for a bias voltage of around 0.450v and that is what the sensor output is with a 95% or higher conversion rate.
In closing, dump the code, if it comes back, if possible, switch sensors (put anti-seize on the threads) and see what happens. If it switches sides, put a new post cat sensor on but dump the code first. It needs to relearn. If not… it is the cat.
If I can be of any more help, just reach out.
Have a blessed day,
Ray