Toyota Nation Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hello... my check engine light is on. I have gone to two different places to have it checked and I received a few different codes. The first came from Midas when I was getting my oil changed. They checked it and came up with the codes P0300, P0301, and P0303. They told me two of the ignition coils needed to be replaced. If this is true do any of you know a way to discover which two need to be replaced or do I just need to replace them all? Or, do you disagree and believe it could be something else?

The second time I went to O'Reillys and they used their code reader and it came up with the code P0420 which I googled and it said it is the O2 sensor below bank 1. Could their be two things wrong? Does anyone know why O'Reillys sensor didn't come up with the P0300 etc codes and vise versa?

Thank you!
 

·
Registered
Joined
·
108 Posts
All of these codes could be correct.

If you are having active misfires you will absolutely know it unless they are extremely intermittent/transient. If a cylinder goes out, or even nearly goes out, consistently the car will run very, very roughly. Also, if there are misfires, and the folks who read the codes at Midas cleared them, they won't be there anymore until the next misfire occurs.

You don't say what car you have, but you'd need to check the cylinder numbering order to know which cylinders are represented by the 0301, 02, etc. The first repair that most try if there are not misfires detected across all cylinders is to change out the ignition coils on the misbehaving cylinders to see if that fixes things.

The P0420 relates to catalytic converter function. If you have a misfire you could trigger this as a result. You also don't want raw fuel that has not been burned being passed through a catalytic converter for any length of time, so if you do get a misfire code thrown again in short order do have that addressed.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #4
Thank you for your responses. Honestly the car runs fine. It is a 2002 Toyota Camry V6. There is no drag in the engine or misfires.
 

·
Registered
Joined
·
46 Posts
Thank you for your responses. Honestly the car runs fine. It is a 2002 Toyota Camry V6. There is no drag in the engine or misfires.
Looks like you have a bad coil in there. P0420 is "catalyst below efficiency" and is likely there because of the misfire. Your engine has 3 coils and spark plug wires that run off to the other 3 cylinders. 1 coil goes bad, 2 cylinders misfire. Be good to get it fixed sooner rather than later. Driving on the misfire will make the catalytic converter get really hot and possible melt it, causing you more problems
 
1 - 5 of 5 Posts
Top