Skip the auto shop - Our mechanics make house calls

Q: My car shows trouble codes P0133 and P0420

asked by on

hello. I had my car serviced about 2 months ago the car's ob was throwing off a p133, p420 and p171.. I took it to the shop, the oxgen sensor was replaced. .I Drove the car for a couple of days and the ob was throwing off just p420, I was told that if i add catalytic converter cleaner to the fuel tank its going to clean the cataltic converter..so i bought the cleaner but a couple days later still get p420. Am thinking ok i might need a new catallytic converter, but since it's expensive i wait until a month later to try to have it replaced..before i have it replaced i check the ob with handheld scanner now am getting a p133 and p420. I should not be getting a p133 since i had the oxgen sensor replaced about a month ago. when i take the car back to the mechanic that replaced the oxgen sensor he tells me maybe i should replaced the catalytic converter first, that the p133 code might go away. i think he is jsut giving me the run-around..can u tell me what to do?? thanks

My car has 182000 miles.
My car has an automatic transmission.

Hi there:

It appears as if you’ve got a lot of miscommunication going on with your mechanic. Here are a few basics. First, anytime an error code is triggered, such as the P0133 OBD-II code the issue needs to be fixed and then the error codes need to be cleared with a professional digital diagnostic tool - not the basic hand held scanner being used. So, before you take it back to this mechanic to get more of a run around (which I agree you’re getting) contact a professional mechanic to complete a simple Check Engine Light inspection. This will allow them to pull all existing error codes, clear those codes and retest the system to determine what is wrong with your Corolla.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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
  1. Home
  2. Questions
  3. My car shows trouble codes P0133 and P0420

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: Is there some sensors activated when shift to reverse that allows engine braking?

Hi there. When selecting reverse from drive on the shifter and the transmission is sticking, check the engine for any broken engine mounts. A broken engine mount will cause a delay in the shifting quality when put into reverse. If...

Q: Vibrating and smoking and oil dumped under car

Hi there. Typically, the engine vibration and shaking is a symptom of a reduction of oil. It's possible that either an oil line or oiling component has broken, which creates a lack of lubrication and tends to cause serious engine...

Q: What is the light reminder?

The light reminder exists to tell you when you have left the lights on. If you turn your vehicle off, and open the driver’s door, but have not turn off the lights, then a buzzer will sound to alert you....

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.