P0421 error code on 2013 Mazda CX-5 Sport
- Thread starter Solan
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- Plano, Texas, USA
P0421 Code: Warm Up Catalyst Efficiency Below Threshold (Bank 1)
With this code if you have replaced both upstream and downstream oxygen sensors and even catalytic converter, and the CEL still lit up, I believe your mechanic used cheap aftermarket catalytic converter and oxygen sensors which may not work to get rid of CEL. A real effective catalytic converter usually costs over $1,000.
How many miles on your 2013 CX-5?
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152k. this is the CAT that was installed.
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- Plano, Texas, USA
I really don’t believe CX-5 uses 2 catalytic converters. Usually with P0421 at your 152K miles, you need a new catalytic converter. Unfortunately a quality CC is too expensive, and the cheaper one may not good enough to get rid of the CEL. Oxygen sensors are similar. Inferior sensors may trigger the P0421 too. And Denso oxygen sensors are the ones you want to use. People dump CC cleaner into the fuel tank、submerge entire CC in a bucket of cleaner、replace oxygen sensors、replace catalytic converters (in sequence) and try to get rid of the P0421 but sometimes just at no avail. Like your mechanic I simply don’t know what is the next step you can do other than spend more money with OEM oxygen sensors and OEM catalytic converter which of course would cost you a lot of money but no guarantee.
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I found this article interesting in that it mentions air leaks as a possible cause of the P0421 code. Just throwing it out there.
P0421 — Warm Up Catalyst Efficiency Below Threshold (Bank 1) – eEuroparts
Dealing with the P0421 code can be tough as it usually means replacing the catalytic converter. Here's all you need to know about this code.
eeuroparts.com
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I bought the OEM post cat (from Mazda parts outlet), and realized there's one in the exhaust manifold too.
I'm dealing with the same code. And I've read it's the CAT IN THE EXHAUST MANIFOLD (PRE CAT).
The code refers to the pre cat. Can't believe I didn't do a more thorough research.
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You can try this. Someone sent it to me after i already got mine replaced. Catalytic converter cleaner best cleaning catalyst solution High Quality dissolve soot & carbon Robot or human?
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Yea the PRE cat cost $700 on the Mazda parts outlet, I paid $666 for the POST cat. (OEM 's)
I mean that cleaner doesn't sound like a bad idea, but I've heard that any cleaner, will ruin the 02 sensors. Which I've replaced since I started there originally.
I have 2014 - CX-5 GT with 190k miles.
At this point I'm tempted to just get a new car.
I also have the other problem, the INFAMOUS KNOCKING SOUND, on the driver side.
It did it with OEM PARTS. So I replaced everything with the suspension, everything under the sun, and the sound it still there.
I'm getting worn out.
(Attached file).
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- 2020 CX-5 GT AWD
Mazda CX-5 has two catalytic converters. The exhaust manifold has an integrated catalytic converter and this is the one monitored by the O2 sensors. As a matter of fact, if you look down into your engine bay, where the upstream O2 sensor is installed, the cat is right under that shield. I've had the same code P0421 (2020 Mazda CX-5) for few months and tried all the things mentioned above but I ended by replacing the exhaust manifold with the integrated catalytic converter. I am almost certain that your Mazda needs a new front cat. See the picture. And, needless to say, my car runs like new.
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Yea, im certain I need one too. But honestly at 190k miles, I don't know how long I'll keep the car.
I mean, my 2008 Honda Civic SI lasted 210k miles.
Plus the knocking sound, I've dumped a lot of money into this and it just seems like it's not going to end anytime soon.
I'll need to do a timing chain, water pump etc that comes with 200k service.
Sorry not trying to get off topic. Just venting.
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- 2020 CX-5 GT AWD
Short off topic: if it's not broken, leaking, don't touch the water pump. Same for the timing chain.
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