Q: Check engine light came on, stayed on for a month, then went off.

asked by on

My cars check engine light came on 5 days after I bought it while I was driving. The VSC TRAC/OFF, and the slippery when wet lights also came on at the same time. I read the codes and it came back P0430, the catalyst system. I cleared the codes and they came back on a few days later, same thing. I've had the car for almost a month now and when I turned it on today the lights didn't come on. I tested for codes after the lights went out to see if it would read anything and the code reader found codes P0430 and P0420 while the lights had gone off. Could this just be a bad sensor. Or do you thinks it's an exhaust leak or a bad cat?

My car has 160000 miles.
My car has an automatic transmission.

Hi there. In most cases, the P0420 code means that either the upstream or downstream oxygen sensor in the catalytic converter is not working. The other code listed tends to be caused by issues with the catalytic converter being damaged. Based simply on the codes, I would wager that your catalytic converter is damaged or worn out and needs to be replaced. However, any mechanic that will make a diagnosis simply by the codes listed is not a good mechanic. So, I would recommend having a professional mechanic complete an onsite inspection to determine what is causing these issues and recommend the right repairs.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Check engine light came on, stayed on for a month, then went off.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Hi Michael. I have a 2007 Toyota FJ Cruiser. The parking brake will not engage. When I pull it up it falls back down. It is rarely

The pawl in the parking brake lever assembly may have gotten out of position and so the pawl doesn't stay engaged with the teeth on the handle lever. A close inspection will reveal a fault like that. As far as...

Q: Can hear fuel injection inside car

If you hear a humming noise, you could have a fuel pump issue. If you hear ticking, then it could be multiple things from a faulty fuel injector, to an engine issue. A diagnostic inspection of the noise from a...

Q: Lean fuel condition and transmission problems

Hi There, There is a good chance that if the fuel cap was left off in a heavy rain that there is a fair amount of condensation or water in your fuel tank, which will definitely cause problems with starting...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.