P0420 2002 Honda Civic LX Cant figure out
#1
P0420 2002 Honda Civic LX Cant figure out
Hi there. I have a 2002 Honda Civic LX with 260,000 miles. I keep getting the P0420 code for the Catalytic system bank 1 (exhaust manifold). I cannot figure out what’s wrong for the life of me.
I’ve replaced the catalytic converter, O2 sensors, PCV valve, spark plugs, air filter, gaskets, and just cannot get it to go away!!!
The car runs perfectly fine which is why I have 0 clue on what it could be. I spoke to my uncle and he said that it might actually be a bad alternator not providing enough juice to the electrical system or even too much. I got it tested and it seems fine.
Any tips?
I’ve replaced the catalytic converter, O2 sensors, PCV valve, spark plugs, air filter, gaskets, and just cannot get it to go away!!!
The car runs perfectly fine which is why I have 0 clue on what it could be. I spoke to my uncle and he said that it might actually be a bad alternator not providing enough juice to the electrical system or even too much. I got it tested and it seems fine.
Any tips?
#3
Everything was from Autozone except the catalytic. I ordered it online. Same store from another cat I bought years ago and never had issues. I thought it was that, got it tested and it’s doing its job
#4
Am assuming you have cleared the codes and it came back??
Then, would suspect you bought an after market O2 sensor??
Honda vehicles are sensitive to aftermarket electronic parts
If you bought Denso O2 sensor and it is the right O2 sensor (downstream sensor)
The you will need a scanner and watch the O2 sensor output on graph and see what it is doing
The downstream O2 sensor should produce a fairly steady state voltage
Note: Ordering on line doesn't mean you always get the real parts
Lots of fakes out there. Hard to tell.
Then, would suspect you bought an after market O2 sensor??
Honda vehicles are sensitive to aftermarket electronic parts
If you bought Denso O2 sensor and it is the right O2 sensor (downstream sensor)
The you will need a scanner and watch the O2 sensor output on graph and see what it is doing
The downstream O2 sensor should produce a fairly steady state voltage
Note: Ordering on line doesn't mean you always get the real parts
Lots of fakes out there. Hard to tell.
#5
Am assuming you have cleared the codes and it came back??
Then, would suspect you bought an after market O2 sensor??
Honda vehicles are sensitive to aftermarket electronic parts
If you bought Denso O2 sensor and it is the right O2 sensor (downstream sensor)
The you will need a scanner and watch the O2 sensor output on graph and see what it is doing
The downstream O2 sensor should produce a fairly steady state voltage
Note: Ordering on line doesn't mean you always get the real parts
Lots of fakes out there. Hard to tell.
Then, would suspect you bought an after market O2 sensor??
Honda vehicles are sensitive to aftermarket electronic parts
If you bought Denso O2 sensor and it is the right O2 sensor (downstream sensor)
The you will need a scanner and watch the O2 sensor output on graph and see what it is doing
The downstream O2 sensor should produce a fairly steady state voltage
Note: Ordering on line doesn't mean you always get the real parts
Lots of fakes out there. Hard to tell.
#7
i’ll let you know if it fixed it by this weekend. I’ll do an Italian tune up too lmao
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