Hi there,

Today my check engine light came on and I checked it with my code reader. I got the code p0430. I looked that up online and it means the 02 sensor is getting a reading that makes it believe the cat needs to be changed, but of course it could be the sensor instead. So I checked the data stream with my code reader and all the sensors were outputting around 0.800 volts except the bank 2 downstream sensor. It was only outputting 0.075 volts.

Now I'm not sure what that means exactly. If the cat was bad, or if I had a leak is that what's to be expected? Or does that indicate that my problem is probably the sensor? Thanks for any tips.

 

Front O2 sensors should be switching high/low. (with .5 volts being the break point.) Rear O2 sensors should also, but, within a narrower margin. If they are remaining fixed, then, they aren't working.

 

I rec you first check the operation of the cat. There are videos for doing this check and you will need a temp sensor gun.
If temps are right with the cats, then O2 sensors would be next to check.
You get the P0430 when cats are below 95% efficiency, so not anything to worry about when light first comes on.
There are gas additives that some have had success with. I tried cataclean then duralube when I got my P0430 with no results.

 

I checked that again. Yes they were alternating, sorry I didnt look carefully.

E=jrsick;3523231]I rec you first check the operation of the cat. There are videos for doing this check and you will need a temp sensor gun.
If temps are right with the cats, then O2 sensors would be next to check.
You get the P0430 when cats are below 95% efficiency, so not anything to worry about when light first comes on.
There are gas additives that some have had success with. I tried cataclean then duralube when I got my P0430 with no results.[/QUOTE]

Ok I should note how this happened. I was driving with 2 cars ahead of me and there were some railroad tracks coming up, so I looked down at them to gauge how bumpy they were and whether or not I should slow down before going over them. When I looked back up the car ahead of me was slowing down fast, so I slammed on the brakes and the wheels locked bringing me to a screeching halt. I didnt hit the car, which is what's most important, but went I went over the railroad tracks when my wheels were locked and not spinning meaning the wheels hit all the bumps rather than rolling over them.

After that I continued driving home and a few minutes later I go that check engine light. When I got home I looked up the p0430 code and saw it could be a leak, which considering the impact made sense. So I went out to take a look and when I looked under the truck there was oil on the ground near the rear. Upon further inspection it was the rear right shock leaking all over the ground. So I order 2 shocks and installed them yesterday. Now I'm planning to bring it to my mechanic next week when he gets back from vacation and tell hime what happened as I'm sure a hit like that could cause all kinds of suspension problems.

For now I'm just wondering what things I should check related to the code, or even other issues that could be caused by something like that?

Thanks for any help

 

I doubt hitting the railroad track had any effect on your P0430. People thrash these trucks all the time.
The P0430 can be a leak, but the leak would need to occur forward of the downstream O2 sensor. This would be either where the exhaust manifolds are bolted to the head, or, where the exhaust manifolds are bolted to the cats. Have you noticed an increased exhaust noise recently? I still think comparing temps at front and rear of the cats would be good info for your troubleshooting.

 

Ok so I ordered a temp gun from Amazon and it should be here tomorrow. I'll check the cat then. Also I've been looking at the cost of a new cat if that's what I end up needing and found the Walker 50551 cat on rock auto.

It says its direct fit, but I'm wondering if it can be clamped, or if it needs to be welded? I've looked everywhere online and cant find a definitive answer. I would assume it just slides over the pipe and can then be clamped, but I just want to be sure. Thanks for your help.

 

You'll need to look at your cat setup to be sure. Unless you've had the truck since new, the exhaust could have been modified.
For my 2008 5.7/1500, both cats are connected via solid exhaust tubing. The exhaust of both cats comes together to a single 3 inch exhaust a few inches behind the passenger side cat. The cats are connected to back half of the exhaust system with a clamp, vice weld.
If you are buying a single cat you will have to do some cutting.
There is a wide selection of pipe connectors and exhaust pipe sealants. You do not have to weld if you don't want to.
You may also want to check the torque on the flange that connects the cats to the exhaust manifolds, torque is 29 ft/lbs.