About 4 years ago, as the cold weather really set in up here in CT my 07 accord threw an P0420 code. I had was not due for my emissions test for another year and noticed no symptoms, so I let it ride. When the weather warmed up, the light turned itself off.
The next year at around the same time, it threw the P0420 code at me again, along with a code for a temp sensor for the cooling system. I had just passed my emissions test shortly before and didn't want to spend the $$ on cat at that time, so I replaced the coolant sensor in the lower part of the radiator and did a drain and fill of the coolant. Shortly after the CE light went out on its own again. I thought maybe the temp sensor was somehow responsible for the P0420 code too.
The next year, when the weather got cold again, what do you know, it threw the P0420 at me again. I let it ride, and again when the weather warmed up the light went off again on its own.
This year the light came on for the P0420 just after I received my emissions test notice at the beginning of December. I decided to try to wait it out, and about 2 weeks later the CE again went out on its own, so the next day I brought it for the test. When I was called up for my results, the guy at the desk said something odd happened, and then proceeded to tell me that I passed the test, but the system showed a P0420 code. He said he had never seen that before, as it should have failed with the code printed on the test result sheet, but not to worry because at the top of the page in bold it showed "passed" and that was all that mattered.
Then just today with overnight temps in the single digits, the light came back on for the P0420.
It has been about 4 years and close to 60k miles since the first time it threw the code. I am good for another 2 years at this point, but the light is annoying to look at and my code reader has never been able to clear this code. Just curious if anyone else has experienced anything similar?
The next year at around the same time, it threw the P0420 code at me again, along with a code for a temp sensor for the cooling system. I had just passed my emissions test shortly before and didn't want to spend the $$ on cat at that time, so I replaced the coolant sensor in the lower part of the radiator and did a drain and fill of the coolant. Shortly after the CE light went out on its own again. I thought maybe the temp sensor was somehow responsible for the P0420 code too.
The next year, when the weather got cold again, what do you know, it threw the P0420 at me again. I let it ride, and again when the weather warmed up the light went off again on its own.
This year the light came on for the P0420 just after I received my emissions test notice at the beginning of December. I decided to try to wait it out, and about 2 weeks later the CE again went out on its own, so the next day I brought it for the test. When I was called up for my results, the guy at the desk said something odd happened, and then proceeded to tell me that I passed the test, but the system showed a P0420 code. He said he had never seen that before, as it should have failed with the code printed on the test result sheet, but not to worry because at the top of the page in bold it showed "passed" and that was all that mattered.
Then just today with overnight temps in the single digits, the light came back on for the P0420.
It has been about 4 years and close to 60k miles since the first time it threw the code. I am good for another 2 years at this point, but the light is annoying to look at and my code reader has never been able to clear this code. Just curious if anyone else has experienced anything similar?
