2010 Honda CRV P020 code...help!
Hi All,
My daughter recently purchased a 2010 Honda CRV EX w/121K a few months ago. I replaced a leaking radiator, all the brakes and rotors and changed all the fluids. We know the car was well kept because she purchased from a relative who had good records.
A few weeks ago a P0302 engine code came on and the car stumbled a few times than ran fine. I thought it would be prudent to replace all the spark plugs and coil packs, My son-in-law did the labor. N codes the car ran great.
Yesterday a P0301 code went off. Being the parts were new I removed the plugs and coil packs to insure that they were installed properly. I found that the cylinder #1 plug was loose and when it was removed it was missing the "ground electrode" ??? My son-in-law could not be sure if the electrode was there when he installed it. It was 0 degrees in New York and he was working outside so I gave him a pass :-). I used a magnet in the cylinder to see if it was possibly there with no luck. A few calls to friends said if the piece broke off after it was installed could have left through the exhaust and might be in the catalytic converter.
Next chapter I installed a new #1 spark plug and checked the remaining 3 plugs and coil packs. I started the car and it ran fine. The P0301 code was gone but now I have a P0420 code which indicated an issue with the catalytic converter or a bad "Downstream Oxygen Sensor".
It can't be a coincidence that the Cat or oxygen sensor went bad after I changed the bad plug? If that "ground electrode" went into the cat could that be a possible cause?
I welcome any input!!!
Bob K
My daughter recently purchased a 2010 Honda CRV EX w/121K a few months ago. I replaced a leaking radiator, all the brakes and rotors and changed all the fluids. We know the car was well kept because she purchased from a relative who had good records.
A few weeks ago a P0302 engine code came on and the car stumbled a few times than ran fine. I thought it would be prudent to replace all the spark plugs and coil packs, My son-in-law did the labor. N codes the car ran great.
Yesterday a P0301 code went off. Being the parts were new I removed the plugs and coil packs to insure that they were installed properly. I found that the cylinder #1 plug was loose and when it was removed it was missing the "ground electrode" ??? My son-in-law could not be sure if the electrode was there when he installed it. It was 0 degrees in New York and he was working outside so I gave him a pass :-). I used a magnet in the cylinder to see if it was possibly there with no luck. A few calls to friends said if the piece broke off after it was installed could have left through the exhaust and might be in the catalytic converter.
Next chapter I installed a new #1 spark plug and checked the remaining 3 plugs and coil packs. I started the car and it ran fine. The P0301 code was gone but now I have a P0420 code which indicated an issue with the catalytic converter or a bad "Downstream Oxygen Sensor".
It can't be a coincidence that the Cat or oxygen sensor went bad after I changed the bad plug? If that "ground electrode" went into the cat could that be a possible cause?
I welcome any input!!!
Bob K
Last edited by Robert Koziak; Mar 5, 2026 at 03:36 PM.
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