Q: Q: Check engine light turns on and off

asked by on

Hi, two weeks ago my truck started with engine light, code p0420. After 2 or 3 days turns off by itself. But last week turn on again and didn't turn off. I took it to autozone and they found p0420 and p0430 next two days engine light turns of by itself. What could be the problem? Any advice will be appreciated. Thanks

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

Both of these codes are related to the oxygen sensor readings. More often than not, this will be caused by failing oxygen sensors. There could be other issues that can cause these codes, such as an engine misfire, failing catalytic convertors, or it could mean that the engine is in need of a tune up. It would be best to have a certified mechanic, such as one from YourMechanic, check the readings on the sensors to see if they are performing correctly, or diagnose a possible performance issue.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Q: Check engine light turns on and 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: Failure code P0750

Hey there. The code P0750 pertains to a shift solenoid. I would clear the code and test drive the truck while monitoring the shift solenoid's values and operation. Afterwards recheck for the code, stored or pending. Perform a battery...

Q: Check engine light is on with codes P2063 and P2064

Hello. The codes you are getting are for the exhaust fluid injection system. Most of the time, this is the result of a failure in the fluid sensor. In some cases, the tank and sensor can be cleaned but most...

Q: service awd drive system what does that mean?

It is possible that one of your wheel speed sensors may have failed. I would recommend having your vehicle inspected by a qualified professional to determine the exact cause of the all wheel drive system fault. This will likely involve...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...