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

asked by on August 06, 2017

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.

Check Engine Light is on Inspection $79.99 - $99.99 Get a Quote

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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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

What others are asking

I have gotten my ball joints replaced and a new spindle and my wheel still keep coming off the ball joint keep coming apart

Hi there. Something is apparently being overlooked, concerning the lower ball joint replacement. The lower part of the ball joint is inserted into the control arm (retained by a circular clip) and the upper part is inserted into the steering...

replace head light

To replace the Low Beam headlight bulb on the Driver Side of the vehicle, you'll need the following tools: a 10mm socket with a 1/4" drive ratcheting wrench, a pair of needle nose pliers and a flathead screwdriver. To replace...

Firing order from the front of the engine.

The location of the ignition coil for the 3rd cylinder is the 3rd cylinder back from the front of the engine where the belts are. From viewing the engine from the front of the vehicle, the 3rd cylinder will be...

Belt problem, maybe a pulley problem?

Nothing ruins a nice drive down a scenic road, or worse yet, a rush hour commute, like the serpentine belt deciding to make a run for it. Matters are further complicated when the problem goes further than the belt. There’s...

My Car drives forward not backwards. In N and R rolles forward, but will not roll back. Have to lift front to move the car beck.

Hi there. Make sure the vehicle is on level ground with the engine warmed up when checking transmission fluid. Check the fluid for color, smell, and contamination as these could be telltale signs of what is occurring inside the transmission....

Engine shakes and won't stay running

Without knowing the type of fluid leak I will speculate it is the water pump is leaking and binding up. You may need to get the water pump and timing belt replaced along with the broken motor mounts.

Front passenger tire caved in.

Hello. If the front wheel caved in then it may be possible that the wheel bearing that was freshly installed may have come undone or let go. This can happen if the wheel bearing was not installed correctly. The same...

What gauges and readouts can be found in the instrument cluster?

The center of your driver side console is filled with gauges, meters and readouts that provide you with vital information about the car. Understanding the information found here will help keep you safe and secure while on the road, and...

I need suggestions for how to cheaply seal or cover my sunroof. Please help!

I have seen people seal their sun roofs with a clear vinyl cover (decal type). I would try to find a business that makes vinyl wraps for cars or boats and talk to them. Also, check the fuses for the...

Related articles

The Best Used Cars to Buy If You’re a Painter
If If you’re a painter, and you work for someone else, chances are you don’t care all that much about what you drive, as long as it gets you to and from work reliably. On the other hand, if you...
Top 10 Best-Selling Cars of 2016
Ford F-series pickup trucks, Toyota Camry, and Honda Civic are some of the best-selling cars of 2016 and all deliver on reliability and efficiency.
Should I Buy a Honda Accord or a Toyota Camry?
The Honda Accord and Toyota Camry have been the best-selling cars for 20 years due to their quality and reliability. Find out which is best for you.