Code P0430 and other issues...

'05 4Runner SR5
V6 4.0L
220K

So, I just had my battery, alternator, and serpentine belt replaced (attempted myself but bottom bolt was seized) and I've had a couple of issues since. The day I picked up my car, I drove it a little bit and made a couple of stops and got home fine.

The next day (with about 3-4 gallons per in her per the fuel gage), she starts losing power and surging on me and I notice the battery light come on. Well, then she quits when I start going up a hill. I couldn't figure out what it was and so after talking to someone, we decided to put a gallon of gas in her. Boom. That got her up and running and since then I've probably put 100-150 miles on her without issue.

And then yesterday, I noticed my code throwing another DTC, this time P0430. After the car has been sitting a while, I do notice that its kind of got a rough start up. But if I crank it once and then drive somewhere, cut it off, and start it back up 10-15 minutes later, I don't get a rough start up response.

I do know there is a code showing that my 4th cylinder is misfiring. This is from about a year ago. My mechanic wasn't too worried about it, so he stored it and the car drove just fine until the alternator acted up.

I'm mostly worried about my catalytic converter obviously. I don't have a couple thousand lying around to fix the issue, but I also understand that a coil-pack can be the issue? If so, should I change the coil-pack and spark plugs and use some Cataclean?

Any guidance would be much appreciated.

 

Update:

Well, as far as the P0430 code goes, I think I've got it figured out. I think it's an O2 sensor. After listening to a couple of opinions from mechanics, I drove my car up a steep hill and didn't lose any power and didn't notice anything odd during my ascension. From what I've read and heard, an O2 sensor will throw it's own code and I believe it did, but a mechanic stored it because he said it was nothing to worry about. Well, I think that O2 sensor should be replaced. I'm guessing that's what causing the intermittent issues.

So, my plan is to replace the O2 sensor with a Denso product and then change sparks and coil packs.

Any guidance would be helpful.

 

Yes, make sure to use a denso sensor, I have read about Toyotas being sensitive to other brands. It might be a bit of a bear to get the sensor out so consider soaking it with a penetrating oil the night before. Also I would buy it from a reputable place and avoid Amazon as there are many counterfeit products on there. The plugs and coil packs are a pretty easy job on the 4.0 especially the passenger side. If you have a little bit of mechanical knowledge none of this will be a hard job.

 

Any update on this?

I also have a 2005 SR5 V6 at just over 180k with P0430 lights flying followed by what I can only describe as a dragging engine, lights will go away for an unknown reason or after I use Cataclean. I just replaced the spark plugs and coil pack. I am terrified it's the catalytic converter. I likely will be going to the mechanic today which I have been avoiding for fear of what he is going to tell me, haha.

 

Hey Lizardhusky, I haven't officially had my CAT tested, but a mechanic I trust told me that to find a steep hill and if it can climb that steep hill without any noticeable issues you can feel, then it's probably an O2 sensor that's under-performing. My neighbor is a Toyota Master Technician (T-Ten) and he said it is possible that the downstream O2 sensor is the problem, but it isn't throwing the code (don't remember the specifics). From what I've learned, I'd let your gas tank get to about a 1/4 or as empty as possible and fill it up with premium gas or if you can find 100% gas (no ethanol) and then clear any DTC codes and see if it comes back before being too worried. Also, running things like Cataclean and Seafoam through your fuel system can change the fuel trim from my understanding which can affect the O2 sensors' readings.

I'm just relaying what I've learned. I'm not a master technician.