Code P0143

[larspetter123]

Hi,
I get CEL and code P0143 when driving for a few miles. I clear the code, and after driving a few more miles, the CEL comes on again and the code P0143 is back. P0143 is related to the sensor after the cat.

The cat on my car was replaced last year, but the code appeared for a couple of months ago, so I do not think the cat is the cause here.

Any of you experienced this code and found a fix for it?

[Leeann_93]

When they replaced the cat, did they also replace the downstream O2 sensor?

If not, it is possible it has failed. Best thing would be to,get it on a scanner and look at the O2 sensor live data.

[AstroWill]

A leak in the exhaust can cause this, I would check that first, then visually check the wiring and connector while you are down there, if it all checks out, then it's most likely the sensor. Spray some penetrating oil(like PB Blaster) on it a few hours or a day before you try to remove it. If you know you are replacing the sensor, it may be easier for you to cut the wire off so you can use a deep socket on it. You could test the wiring with a volt meter as well. New sensor will cost $20 - $60 depending on which one you get, I would get the cheapest direct fit one available. It's only job to to make sure that the cat is working.