Catalytic converter failed at 45k miles

[Jayp08]

Hello everyone. I bought a used 2020 ford ranger last summer. Last week the check engine light came on while driving, and the car threw a p0420 code when I checked. Since the power train is still under warranty I took it to my local dealer.

A week later they called me, said the truck was ready and it was indeed a p0420 and the catalytic converter needed to be replaced. I asked if someone knew why the cat failed so early and no one could give me a thoughtful reason. The answer was they saw the code, replaced the cat, and all is good. I am wondering if any one else on this forum with more experience can hypothesize as to what caused the early failure. The truck is used and had a clean carfax but that doesn't mean the maintenance was kept up.

I've read up on head gasket issues with the 2.3s and I am wondering if the early cat failure is a sign. I have not seen white smoke coming from the tail pipe, the oil looks fine when I pulled the dipstick, there was no residue under the oil cap, and I didn't see the coolant bubble. Could it just be a bad part? Interested on what other members may think. Thanks.

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[RedDakooter05]

Wow, they didn't even bother to investigate why it failed... Hate dealerships so much.

As far as I'm aware, 1) Only one other user had a headgasket issue and 2)This was more of an issue on the focus I believe. The ranger has an updated design.
(Could be totally wrong on this claim)

Cats on the other hand, well they can fail early on even with well-maintained vehicles so I think you just had a bad unit. You can always have a shop look for internal coolant leaks.

 

[9zero1790]

wow that is low miles for a cat to fail. I wonder if it something with computer issues or sensors being bad. I would almost bet the actual converter was likely ok, but the electronics jazz on / in / or connected to the cat may have been the issue. glad the dealer got it fixed up.

 

[dtech]

Cat carries an 8yr/80k miles warranty as an fyi - longer than powertrain. video of reverse cat kill. IIRC the dtc is from a comparison of front and rear O2 sensor readings, but I would think they might test the sensors before just replacing the cat and conducted a tailpipe emissions test.

 

[airline tech]

P0420 is the post cat o2 sensor reading constant reading above the 450 split threshold - measures cat efficiency
Should stay steady and not fluctuate
Spec is .41 volts

Pre-cat sensor should bounce rapidly from low to high on both sides of 450
Rare for them to fail - at that low mileage - coolant leak will cause them to fail most often - but it has to be a bad leak - enough to have constant flow into the exhaust - you would have definitely noticed it

 

[Wytchdctr]

The 2.3 head gaskets issues wasn't the Rangers, wrong gasket on the RS. Also, we have the cross drilled block between cylinders vs the top cut block (like the pre22 ish 2.0 ecoboosts) for coolant passages so we should be OK from that issue as well.

So many head gasket issues with Ford 4cyls.. but we seemed to dodge them like Neo with bullets flying by....

** I saw some posts from members seeing failures in explorers etc.... and I think that is the same setup as ours.. so it is possible.

 

[Jayp08]

Thanks everyone for your replies. I feel better hearing that not too many, if none at all, head gasket failures have been prevalent on rangers. I also was not sure if my year (2020) ranger had the cross drilled coolant canal design rather than the open deck design at the top of the block. I will keep an eye on it. The engine sure feels like it's running fine.

 

[Wytchdctr]

If I can find the link to the 2019 design I'll post it. They mention the cross drilled there from the start and beyond. I wasn't sure either until that.

Maybe because of the possible towing stress... dunno but it's good.

 

[Max Crafter]

previous owner may have been using an octane booster with MMT

 

[OldBill]

Octane booster or some other fuel additive used in excess amounts was my first thought. A buddy of mine owns an excellent exhaust and brake shop and I remember him talking about "how cheap" they make everything now and he has seen brand new Catalytic Converters just fall apart inside due to poor quality materials, shoddy workmanship and bad design !

 

[Jacob]

Octane boosters, fuel system additives/cleaners, burning oil/coolant, unburned fuel.
I know people have been big into making the pop sounds from exhaust now a days. They might have been doing that with the truck before it became yours.

 

[Treesh66]

I’m curious if you also had the wet spark plug issue too. I just had to replace 3 coils and plugs on my 2019 XLT at 59,000 and the dealer said if I didn’t that the unburned fuel could cause the cat to fail. Hate dealership. And I am no expert!

 

[Jayp08]

Not sure since I bought the car used. There were no symptoms prior to failure of the cat, nor when the I got the check engine light. I've also read about the spark plugs getting wet with heavy rains due to the hood design. I live in Miami and it has been raining like crazy here, and I've checked the top of the motor after a storm passed and it looks dry to me, so I think I may be lucky and immune to that issue. I do plan on ordering an engine cover for it soon just to be safe.

 

[bruhbruh]

I just went through a similar situation. 24k on my 2021 Lariat and I've been the only owner. Everything has been great, but while on a road trip I popped a P0420 code. No drivability issues. Dealer replaced the catalytic converter under warranty. I buy normal gas at normal places. Dropped the truck off at 7am and they had it done by 3pm. Not too bad. Service manager said this was the first cat replacement they've done on a Ranger.

 

[EJH]

My mother's 2022 Edge needed a new catalytic converter within the first 10-15k miles or so. Dealer replaced it under warranty.

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