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I have 2010 honda accord lx. How can I solve this code? Looks like I need an oxygen sensor bank 1. But I don't know part number for that and its location.
 

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Yea I modded my car again
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p420 is typically a bad cat converter. Replacing the o2 in that event would be pointless. You need to inspect the cat converter internally to determine if its damaged or not. Then you'll know if it's the downstream sensor or not or a ruined cat converter. And if it's a ruined cat converter then you likely have other issues causing it to degrade and then definitely a good mechanic is required to read the live data of the car to determine if something is out of wack causing this issue.

With all due respect, if you cannot google ur car and figure out what o2 sensor goes in ur car, nor find the location of it, this may be more than you should be doing yourself. I just googled ur car and added o2 sensor. 2nd link that popped up has all of them listed :


Upstream sensor is before the cat (above it)
Downstream sensor is after the cat (below it)

Downstream sensor is the one that will give you a p420 code.

You could try replacing it and seeing what happens, but it may very well not work. Once you clear the code it can take up to 50 miles or so of driving to show itself again by the way.
 
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Sometimes some routine maintenance can solve this code. Start with simple things, then fix things that are a problem.
  • Air filter New/Clean
  • Clean MAF
  • Air intake hose leak free
  • Repair any vacuum leaks
  • Spark plugs New/Clean
  • Spark plug tubes oil free
  • Coils firing, oil free
  • PCV valve replaced
  • EGR valve replace (150k +, if unexplained rough idle)
  • Use Full synthetic oil (recommended weight)
  • Top Tier 87 octane fuel or use fuel injector cleaner
As said, replacing an O2 sensor will not solve a maintenance issue. It is best to cure the cause than treating the symptom. If the above things do not cure your emission code after a few thousand miles, the damage to the catalytic converter may be to great to overcome and will need replacing.
 

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Discussion Starter · #4 ·
Sometimes some routine maintenance can solve this code. Start with simple things, then fix things that are a problem.
  • Air filter New/Clean
  • Clean MAF
  • Air intake hose leak free
  • Repair any vacuum leaks
  • Spark plugs New/Clean
  • Spark plug tubes oil free
  • Coils firing, oil free
  • PCV valve replaced
  • EGR valve replace (150k +, if unexplained rough idle)
  • Use Full synthetic oil (recommended weight)
  • Top Tier 87 octane fuel or use fuel injector cleaner
As said, replacing an O2 sensor will not solve a maintenance issue. It is best to cure the cause than treating the symptom. If the above things do not cure your emission code after a few thousand miles, the damage to the catalytic converter may be to great to overcome and will need replacing.
I bought an o2 sensor yesterday for 45 bucks. That's the easiest way for solving if it solve. I also have unstable acceleration due to the code. It just need to pass inspection and next month is inspection date.
 

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I bought an o2 sensor yesterday for 45 bucks. That's the easiest way for solving if it solve. I also have unstable acceleration due to the code. It just need to pass inspection and next month is inspection date.
Did you buy a Denso or NTK O2 sensor? All others seem to not work well on Honda vehicles.
 

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I also have unstable acceleration due to the code.
Poor acceleration could very well be a clogged cat. Hopefully a new O2 sensor will get you through inspection.
 

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I see by your first post 1 of 4 codes? What are the other 3 codes? If you have other codes you should fix those first as the P0420 may be caused by another problem such as a misfire.

P0420 is not an error, it is a result. There is a lot of reasons that a P0420 is set. Lots of questions.

Is this a 4cyl or V6?
Does the engine burn oil or antifreeze?
How many miles on the engine?
How many miles on the sparkplugs?


What information is in the freeze frame data?


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07 Accord Sedan EX V6 Auto
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If you need to pass emissions, clear the code, then drive the hell out of the car for about 10 miles, and give it lots of full throttle. Putting lots of heat into the cat should burn off any contamination in it and on the oxygen sensors. I've seen it work more often than bot, and is a whole lot cheaper than I new cat.
 

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Clearing the codes does not work. When the codes are cleared so are all of the readiness test, that is done as part of the drive cycle which takes days to complete. Those readiness test must complete before you can have the car tested. It may be possible to have all the subsystem tests complete except the Catalytic converter. In most states you are allowed 1 subsystem to be incomplete, but not in California for sure. The key is to know all the rules.

Depending on what is causing the P0420 driving it harder and getting the temperature up in the Catalytic converter may work, but it may also melt it.

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