How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Richard Your Own Question
Richard, ASE Certified Technician
Category: Honda
Satisfied Customers: 15491
Experience:  Honda tech. ASE certified technician
Type Your Honda Question Here...
Richard is online now
A new question is answered every 9 seconds

Honda accord My check engine light came on in my 2005 Honda

This answer was rated:

My 'check engine light' came on in my 2005 Honda accord. Mechanic says it indicates a possible problem with the cataletyic converter. Preliminary test is to turn the light off and drive for 15 minutes at speeds between 50 and 60 MPH. If that doesn't keep the light from coming back on then the cataletic converter should be replaced. What's this all about?????

Hello and welcome to



Was the fault code P0420? How many miles on your vehicle?

Customer: replied 6 years ago.
I don't know the code --- just that he said that it indicated the Cat C. The Honda has 61000 miles on it.
Ok If you do need to replace the cat you should go to your local Honda dealer as the converter should be covered under the federal emissions warranty for 8 years or 80,000 miles.
Customer: replied 6 years ago.
But what's this business about driving for 15 minutes at 50 to 60 miles an hour? If the light is reset can doing this possibly solve the problem?

Basically the engine management ECU will run a test on the converter during a drive cycle. The cat monitor cycle involves driving on the highway at a steady speed for an extended period of time. If the light does not come back on then this does not mean the converter is not faulty. If the light or code returns then you will need to replace the converter.

Customer: replied 6 years ago.
What? "If the light does not come back on it DOES NOT mean that the converter is not faulty? Then what is the driving test for? One last question. Will a problem of this nature affect gas milage?
If you drive your vehicle for 15 minutes at highway speeds the light may not come on as it takes two trips through the cycle for the light to come back on. I recommend you drive your vehicle then re check it for stored fault codes. If the cat converter code returns it will need to be replaced. Since the cat is not working properly this can effect fuel economy but you may not notice a big difference.
Richard and 4 other Honda Specialists are ready to help you
Customer: replied 6 years ago.
Thank you, Richard.

You are very welcome. Let me know if you have any further questions or concerns.


Thanks for using