I have a 2004 acura tl that the check engine light is on for couple days then it would go off for a couple days then it will come on again. It's been doing this for a year now, but the car still runs fine. The car have 122000k mile on it. When the CEL went on i took it to autozone and they pull out code P0420 and only that code. Does anyone know or have any problem similar to this? I'm thinking it must be my cat converter or o2 sensor that hasn't gone totally bad yet.

 

Aha... sounds to me like your in need for the ever famous ECU reflash acura did to our 2004 TL's. Does it turn on after some hard acceleration?

Also have you had all the services done?

 

It will turn on after hard acceleration but not all the time. It happens every time after i refuel my car. I know for sure i tighten the fuel cap. If they did do a ECU re flash how much with the cost?

 

I just got check engine light on, in the weekend when I was coming home from a trip to Montreal Quebec. I felt a decrease in acceleration and power overall. I took the car to my mechanic this morning and he read the code - P0420. He told me that can be 3 cases: 1) bad gas with water or other impurities; 2) catalytic convertor sensor or 3) worst case, the catalytic convertor need to be replaced. He didn't erase the error code till i deplete the whole gas tank and fill up with good premium gas. It is really strange because at the service center on the 401 highway I specifically asked for premium gas and " premium" I got(this was during the trip). Right at the highway exit I refilled from s**ll with v power premium about half tank. the car was parked over night and in the morning the power was back but the light still on. After the trip to the mechanic the error disappeared. I'm confident that it was in my case just the bad gas and i will ask my mechanic to put some additive in the gas tank to flash the water out.