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

asked by on December 19, 2016

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.

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