code 67 Catalyst low efficiency.

[filipinoy06]

what this code mean? how do i fix this? thanks!

 

[mjones73]

It means the ECU doesn't think the cat is performing correctly anymore. It compares the exhaust from the O2 sensors in front and behind the cat and if doesn't see the proper difference it throws that code.

It could be one of your O2 sensors is off or the cat is just not working correctly anymore.

 

[filipinoy06]

so how do i make sure which one is not working properly? i wanna make sure first before i change the sensor or the cat.

 

[TheIVJackal]

To check the O2 Sensor you would have to backprobe it and check it with a DMM or a DSO. How many miles are on your car and how old is it?