A few days ago, my wife's 2004 RX330 with over 100K miles had a check engine light and VSC light came on. She complained about the lack of power and engine shaking. She said she also smelled a little bit of exhaust or gas. I used a generic OBDII scanner and got P0306 which indicated cylinder 6 misfire. The engine RPM raced up and down, and there's a small ticking sound every few seconds.

I was really worried there may be a mechanical issue with the engine. Luckily cylinder 6 is very easy to access and I swapped the ignition coil between cylinder 4 and 6. After clearing the code, I restarted the engine. The misfire moved from cylinder 6 to cylinder 4 with code P0304 and VSC light, that was a pretty good indication of a bad ignition coil. I ordered the Denso (OEM) ignition coil from Amazon with 1 day shipping, replaced the #4 ignition coil. The engine is running smoothly again. The job took about 5 minutes, but evaluating the result is going to take a little bit longer.

I want to share my fixes with you, if you have a P030X problem, check the easy stuff the ignition coils and spark plugs first and ignore the VSC light until you fix the more critical code first. If you got the odd number cylinder misfire, you are into a bigger job than you have the even number cylinder because the odd number cylinders are a lot more difficult to get to. Good luck.

 

Thanks for sharing, great information to keep in mind.

 

I had the same thing happen to me and we were able to get the ignition coil changed pretty easily. For some reason, the VSC light is still on. Any advice on what I can do? Thanks.

 

I also have the CEL and VSC light on and the shop checked the code and said it was a bad Cataletec converter by the engine manifold? estimated fix was $800.

 

That sounds more like a P0420 or P0430 code or both, did you ask which code it was?
There are many variables to verify before replacing a catalytic converter, it could be anything as simple as a faulty or not put on correctly gas cap.
The Check Engine & VSC Light was on when I first purchased my RX330.
The Code P0420 & P0430 came up with my scan tool, in my case, I erased the code & kept filling up with Esso 91 Octane (in Canada).......
Check Engine & VSC Light never came back on.

 

My RX350 threw a P03050 the other day so I got a new coil and decided to change the plugs too. I just got back from fixing it with my mechanic. We had the fight off the stupid intake plenum and once that was off, 2 of the ignition coil boots got stuck down in with spark plug, one in the back and one in the front. After removing the spark plugs that were already there, we noticed the new sparks plugs were longer. After a quick check online whoever did the previous job used the wrong plugs and they weren't even iridium. After getting it back and assembled it runs great if not better I feel. We also left off the left most bolt on the back of the plenum in case I have to replace any other coil again later.