# 2011 Nissan Sentra p0420 **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** nissan, catalytic-converters, sentra, diagnostics\ **Created:** [October 12, 2021, 8:48pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920 "2021-10-12T20:48:47Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![mkluza98\_177643](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@mkluza98\_177643](https://community.cartalk.com/u/mkluza98_177643)\ **Post date:** [October 12, 2021, 8:48pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/1 "2021-10-12T20:48:47Z")
I have a 2011 Nissan Sentra. It has had the following codes for 1.5 to 2years. Primary DTC P0420 Secondary DTC P0430 Catalytic converter below threshold bank 1 I feel no loss in power. It idles a little rough but not bad. Would it be the O2 sensor or catalytic converter? Any help appreciated. I also saw that a miss fire might cause this issue. I have new plugs and wires ordered. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 12, 2021, 8:53pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/2 "2021-10-12T20:53:38Z")
A bad O2 sensor will set an O2 sensor code. A bad cat will set a cat code. Evey vehicle I’ve had in the shop with a P0420 DTC turned out to be because of a bad cat. Tester ---
**Author:** ![mkluza98\_177643](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@mkluza98\_177643](https://community.cartalk.com/u/mkluza98_177643)\ **Post date:** [October 12, 2021, 8:59pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/3 "2021-10-12T20:59:07Z")
Dam, I was hoping it wasn’t a catalytic converter. Oh well thank you very much for your help. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 12, 2021, 9:01pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/4 "2021-10-12T21:01:17Z")
> [@mkluza98\_177643](#): > > Dam, I was hoping it wasn’t a catalytic converter. Everybody does when the computer displays the dreaded P0420 DTC. Tester ---
**Author:** ![mkluza98\_177643](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@mkluza98\_177643](https://community.cartalk.com/u/mkluza98_177643)\ **Post date:** [October 16, 2021, 6:47pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/5 "2021-10-16T18:47:29Z")
I went to change the spark plugs. From left to right spark plug wells #1 had a lot of oil. #2 dry (No oil) #3 oil residue #4 practically full of oil I’m planing on changing the valve cover gasket and well seals. This would cause a the engine to not run efficiently. Could this be the culprit of the P0420 code or could it have cause my catalytic converter to go bad? ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [October 16, 2021, 6:51pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/6 "2021-10-16T18:51:51Z")
Misfires definitely don’t help, in regards to catalytic converter longevity But my gut feeling is your catalytic converter has degraded to the point where P0420 set Definitely no exhaust leaks? P0420 usually sets and the car “feels fine” . . . fwiw ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 16, 2021, 6:55pm UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/7 "2021-10-16T18:55:02Z")
Have someone connect a scanner to the vehicle to monitor the O2 sensor after the cat to determine if the cat is bad. [![](https://global.discourse-cdn.com/cartalk/original/3X/9/2/920c82aae79279b7169d496b337e65aa8eb81476.jpeg "Using upstream and downstream oxygen sensors to test the catalytic converter") ](https://www.youtube.com/watch?v=KGpMzdEO5KY) Tester ---
**Author:** ![mkluza98\_177643](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@mkluza98\_177643](https://community.cartalk.com/u/mkluza98_177643)\ **Post date:** [October 17, 2021, 5:08am UTC](https://community.cartalk.com/t/2011-nissan-sentra-p0420/179920/8 "2021-10-17T05:08:01Z")
I will have it tested and reply with the results thanks