I know an auto forum would be the best place for this question, but I don’t have a presence on any. I also know the collective forum knowledge will probably have an answer

Could a broken engine air intake hose cause the catalytic converter to throw a code?

07 Honda Odyssey. Was driving home tonight and the check engine light came on. Put on the OBD reader when I got home and got code P0420, which is the catalytic converter. The lowest hanging fruit for causes was a clogged air filter. I was pretty sure that was fine, but it’s also the easiest to check/fix. It was extremely clean, but I found that the air intake hose was brittle and cracked in several places. If that’s causing air problems and messing up the fuel/air mix, could it register as an issue way at the other end?

I’m going to replace it first thing tomorrow morning because it’s bad, but do I have any chance of actually fixing the code I have? If that does fix it, how long might it take for the code to clear on its own? Or, do I need to clear it myself and see if it trips again?

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BernDog
...clear it myself and see if it trips again?

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SDGuy

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BernDog
...clear it myself and see if it trips again?

Wanna give me any odds on that being the issue?

There is a chance that could be the cause of the error code if the cracks in the intake are after the mass flow sensor.

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P0420 can also be an evaporative leak, so you're probably on to something with that diagnosis.

Clear the code rather than letting it clear itself in case that you don’t have the correct fix.

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Filliam H. Muffman
There is a chance that could be the cause of the error code if the cracks in the intake are after the mass flow sensor.

Not sure what that is. The cracks are between the air filter and the engine. I’m far from a mechanic. Mostly what I know about cars is what I can find from googling problems. My theory, though, is that the engine is getting too much air, throwing off the ratios, and causing the code. All I know is that I had a code and found a problem that may be related.

My googling since posting has also shown that the catalytic converters could be nearing end of life on a 15yo car.

I’m also learning about cleaning catalytic converters. If fixing the air leak doesn’t solve the issue, I may try some voodoo before going to the mechanic. While the solutions I’m reading about may or may not work, they seem fairly safe to try.

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BernDog

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Filliam H. Muffman
There is a chance that could be the cause of the error code if the cracks in the intake are after the mass flow sensor.

Not sure what that is. The cracks are between the air filter and the engine. I’m far from a mechanic. Mostly what I know about cars is what I can find from googling problems. My theory, though, is that the engine is getting too much air, throwing off the ratios, and causing the code. All I know is that I had a code and found a problem that may be related.

My googling since posting has also shown that the catalytic converters could be nearing end of life on a 15yo car.

I’m also learning about cleaning catalytic converters. If fixing the air leak doesn’t solve the issue, I may try some voodoo before going to the mechanic. While the solutions I’m reading about may or may not work, they seem fairly safe to try.

The MAF (Mass Air Flow) sensor is frequently located on the air filter box. If there are holes in the tube between the sensor and the engine, you're getting a lot of unmetered air entering the engine which throws everything off. Since you know the hose is bad, replace it and reset the codes before doing anything else.

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P0420 is a catalyst efficiency code, not a catalytic converter code.

It's usually not the catalytic converter.

It could be the air intake tube. It could be poorly performing O2 sensors. It could be the wiring harness. It could be the computer.

If you have cracks in the tube, change that first - it's inexpensive, and easy.

You have to fix that hose anyway. fix it, reset the code, see what happens. There is no point in speculating what could or could not be, until you fix what is known to be broken.

Thanks, all. It was always my plan to replace the hose first. Did that this morning and drove a little in and out of town, probably what would be considered a drive cycle. Home for a little bit and started the car again and the CEL is off. Still showing the code after I clear it, but more driving might change that too.

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BernDog
Still showing the code after I clear it, but more driving might change that too.

Unclear on this. You should have an option to "clear all codes", after which the code will not be showing. The only reason for the code to reappear is if whatever is causing it is still there.

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davester

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BernDog
Still showing the code after I clear it, but more driving might change that too.

Unclear on this. You should have an option to "clear all codes", after which the code will not be showing. The only reason for the code to reappear is if whatever is causing it is still there.

The check engine light is off. I clear codes. I rescan, and it’s there again. Seems odd, yes.

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BernDog

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davester

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BernDog
Still showing the code after I clear it, but more driving might change that too.

Unclear on this. You should have an option to "clear all codes", after which the code will not be showing. The only reason for the code to reappear is if whatever is causing it is still there.

The check engine light is off. I clear codes. I rescan, and it’s there again. Seems odd, yes.

Are you starting and shutting off the car in between reads? Odd though, my cars all have the light go off immediately after cleaning.

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