I woke up this morning to a check engine light and the VSC lights. I headed straight to autozone to have the codes read and feared for the worst on my 04 V6 - head gasket issues. I did some searching around here and instead it appears to be emissions related and the things people have done to get fix it don't seem to be particularly cheap(replacing catalytic converters). i want to point out that there are really no symptoms of abnormal behavior at all from the truck. I had to drive 25 miles on the highway to work this morning and it appeared to be fine.

I am trying to get an idea for what my best course of action should be to remedy the problem. Here are the codes:

C1207 - Engine Control System Malfunction

C1223 - Malfunction in ABS

C1246 - Malfunction in Mass Cylinder Pressure Sensor

P0430 - Catalyst system efficiency below threshold bank 2.

this p0430 code showed upf 4 times in the same report.

If I'm not mistaken I believe the P0430 refers to the passenger side cats, but I'm just basing that off of what I read around the forum. Any and all help is greatly appreciated.

Yep, that's usually the down steam O2 sensor after cat converter. My '99 3.4 used to throw that code all the time - it was always lean in bank 2. I purchased and returned a few re-manufactured O2 sensors before buying a new Bosch unit from Toyota. The code cleared almost immediately with the new unit.

I'm not sure if that's your exact issue, but it's certainly worth a look.

I think the VSC lights come on with ANY and ALL codes. Mine have been on for at least 80,000 miles. The code that is thrown is O2 sensor downstream too. When it goes off (turns off the CEL light), VSC goes off too. I 100% ignore the "vsc" lights. SOOOOO much about them on the net. Make sure your gas cap is tight first. That's a known issue which triggers lights.

A Follow Up on my gas cap issue:

1. I went back to my close State Inspection Station today to ask if he could ck my orig fuel cap that caused a Ck Eng and VSC Lights (a cell code and me replacing the cap to clear all). The orig O-Ring appeared flatten vs full shape but regained the full shape in a few days. At that point I felt the flattened O-Ring was not sealing as well, “causing the Ck Engine Light and Cell Code”. The Old Cap passed the test and I have reinstalled but will wait a couple of weeks to feel All Is Well!

2. If All Is Well, it is due to me tightening the orig cap past one click (stated on the cap if you can see black on black vs in the manual on the used 07 purchase.

3. The additional killer was that the After-Market Cap w/n fit the holder on the fuel door, nor did it have a holding strap. Well! The Auto Store said they have no problems taking it back.

Good Luck on your issuer!

I had a couple of those codes pop up recently. Cleared them out and next time I filled up I cranked on the gas cap excessively and since have not had the codes come back, it's probably been 9000 miles since. My cap is not the one click type.

I have the 0430 code in now. I bought a couple non-fouler kits from napa and I have drilled them out. Hoping to get some time soon to install them. This will also give me the motivation to do the vsc off mod because I have enjoyed being able to spin the tires and rally around snow packed roads!

I JUST had this happen to me a couple days ago. I was looking on here about it and people mentioned the gas cap so I went out and it was really loose so i tightened it and it took a few days but I noticed today that the lights finally went off so I'm assuming that was the issue.

Has anybody come across a guide step by step guide on how to replace the sensors? I'm much better with a hammer and nails, but am not afraid of the wrench. If there's a step by step or a video somewhere that anyone has found, I'll try it myself.

I just spoke with a friend who works at a local toyota dealer. He said that P0430 is caused by bad Cat, and that the cat would need to be replaced. The part alone is like $1100. Has anybody had success with just changing the O2 sensor? Also, if a code is saying "left bank" is that referring to the drivers side or passenger side?