Q: Check Engine light comes on, mechanic replaced o2 sensor but light still comes on.

asked by on

Check engine light comes on, mechanic ran diagnostic and said it needs o2 sensor replaced. He replaced it but light still comes on. Mechanic ran diagnostic again and said it still is showing bad o2 sensor but since he replaced it the problem must be a catalytic converter that is plugging up and should be replaced. Since replacing a converter is costly I want to make sure this is the problem. My question; could this be something else or does the converter need to be replaced? Second question, is it okay to run the vehicle if the converter is the problem?

My car has 122000 miles.
My car has an automatic transmission.

Hi there:

If the mechanic completed the O2 sensor replacement, reset the codes and the error code was triggered again, it is possible that the catalytic converter is damaged and needs to be replaced. However, it’s also very common for the electrical harnesses that power these sensors to become frayed, damaged or faulty; which can also trigger the check engine light. It’s not advisable to drive a vehicle with a damaged catalytic converter for extended periods of time, as it can cause damage to internal engine components.

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 comes on, mechanic replaced o2 sensor but light still comes on.

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: when coming to a stop, my truck has a binding/clunking noise in the rear end

Hello, thank you for writing in. While the components you have looked into are great inspections considering you tow often, lets start a little simpler and work our way down the list. Since this is happening while you are braking,...

Q: How bad is it to repair a ball joint and CV axle?

You are looking at a lengthy repair. There are several components that will need to be replaced. It is hard to say how rough the removal and installation of these parts will be, because the amount of damage that has...

Q: Tries to run but won't get over 400 rpm before dying.

Hi there. Check for the three essentials that the engine needs to run, fuel, spark, and air. If you are having fuel and the pressure is 30 psi or higher, then check for spark on the spark plugs and wires....

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...