# Repair or sell? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** toyota, camry\ **Created:** [October 2, 2017, 6:42pm UTC](https://community.cartalk.com/t/repair-or-sell/108296 "2017-10-02T18:42:22Z")\ **Posts on this page:** 1\ **Showing post:** 26
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [October 4, 2017, 1:45am UTC](https://community.cartalk.com/t/repair-or-sell/108296/26 "2017-10-04T01:45:55Z")
> [@dmerle1](#): > > It is showing a P0420 code (which keeps coming back after I clear it (with my ScanGauge That’s the code for a potentially faulty cat, but it doesn’t necessarily mean the cat is the problem. Take a look at the post by Tester below which shows how the computer compares the pre-cat O2 sensor signal to the post-cat O2 sensor signal. You need to make sure that same test has been done on your cat, and it shows the cat is bad, and not some other problem, like a bad or disconnected O2 sensor. > [@Has my Catalytic Converter gone bad and is it worth it to replace it?](https://community.cartalk.com/t/has-my-catalytic-converter-gone-bad-and-is-it-worth-it-to-replace-it/107714/2): > > p0420 is reduced catalyst efficiency - that doesn’t always means the cat is bad, especially when you have a misfire. P0502 is the vehicle speed sensor which should have no effect on misfires.problem or take it to So to answer your questions, Yes, use a pressure tap into the forward O2 sensor and run the engine open loop to check backpressure You have several places to insert the pressure taps, test, and decide which cat is clogged, if, in fact, they are. No, this is time for you to properly … --- _[View the full topic](https://community.cartalk.com/t/repair-or-sell/108296)._