My 2016 GC with the 3.6 has CEL on with P0420 and P0430 codes. Help.

385 Views 7 Replies 3 Participants Last post by Guk66, 3 mo ago

Kevin910_

Discussion Starter · 3 mo ago

Like the title says, but the thing is that I removed the downstream O2 sensor on the right bank, looked inside the honeycomb, and it looks pretty good. I can imagine the left is pretty much the same. On the other hand, the sensor tip looked a bit like if it has light rust on it. Can it be merely a bad O2 sensor that triggers my CEL? The coloration of the sensor doesnt seem to me like if the engine is passing oil, fuel or coolant to the exhaust. Also, my exhaust has the rotten egg smell.

Automotive lighting Audio equipment Liquid Circle Eyelash

Automotive lighting Audio equipment Circle Close-up Automotive tire

Automotive tire Gas Tints and shades Circle Electric blue

See less See more

Save

1 - 8 of 8 Posts

Crosshairs

· #2 · 3 mo ago

That's an odd color for an 02 sensor..are you using a fuel additive ?
but to answer your question, yes a bad 02 sensor can cause that code, but both left and right sensors being bad is not likely

Save

Kevin910_

Discussion Starter · #3 · 3 mo ago

Crosshairs said:
That's an odd color for an 02 sensor..are you using a fuel additive ?
but to answer your question, yes a bad 02 sensor can cause that code, but both left and right sensors being bad is not likely

When the light came on, I used Cataclean only once, and recently I used AmsOil gasoline fuel additive to help clean the system. Only once as well.
By the way, first it was only P0420, and then a few weeks later, P0430 appeared.
I might think poor quality fuel was used before I had the car and also, the car was a bank repo before I bought it. It was sitting for a year. Maybe gas went bad and fouled up the O2 sensors.

Save

Crosshairs

· #4 · 3 mo ago

It cant hurt to replace both sensors first , because even if you do end up replacing the cats, it's a good idea to replace them at that time

Also, air leaks can cause those codes, so make sure you dont have any leaks and be sure the upstream 02 sensors are tight if they were removed .

Save

Reactions: 1

Kevin910_

Discussion Starter · #5 · 3 mo ago

Crosshairs said:
It cant hurt to replace both sensors first , because even if you do end up replacing the cats, it's a good idea to replace them at that time

Also, air leaks can cause those codes, so make sure you dont have any leaks and be sure the upstream 02 sensors are tight if they were removed .

Will check the upstream sensors as well. The 1/1 is kind of tough to get to. Has lots of hoses and wires around it. I may remove the 2/1 sensor to check it out and try to see something inside the cat at that point. I dont believe I have air leaks anywhere in the system. How can I check that without major dissassembly?

Save

Crosshairs

· #6 · 3 mo ago

Kevin910_ said:
Will check the upstream sensors as well. The 1/1 is kind of tough to get to. Has lots of hoses and wires around it. I may remove the 2/1 sensor to check it out and try to see something inside the cat at that point. I dont believe I have air leaks anywhere in the system. How can I check that without major disassembly?

A smoke test is the best way, but I doubt you have a smoke machine..

Other than that, a quick and dirty way is to look for soot marks around the joints or have someone block the tail pipes while its idling and listen for air leaks

Save

Kevin910_

Discussion Starter · #7 · 3 mo ago

I will replace all the O2 sensors. That one I removed does have an odd color. That doesnt make me too confortable about the other sensors. If that doesnt clear the code, then ill think about the cats.

Save

Guk66

· #8 · 3 mo ago

Sorry you're having trouble. I would suggest checking your battery, low voltage can cause all sorts of strange codes. I recently went through similar situation that cleared themselves after replacing the battery. Good luck.

Save

1 - 8 of 8 Posts

Top Contributors this Month