I got the TRAC OFF and Check Engine light on our 2012 Lexus RX 350 on Friday. The car starts fine and drives for a bit before getting the "stumbling" feeling from the engine. I did fill up on some 88 octane just prior to this and forgot to check the amount of ethanol in it. I found out after the fact that this is a 15% ethanol product. The owners manual says not to use an ethanol mix of greater than 10% (Grrrrr was only paying attention to the Octane numbers).

Autozone free engine light check shows code showing P0346 - quick check online shows possible bad coil on cylinder 6.(3 instances found)
Could this be caused by the "bad fuel" or did this fuel just push a part past it's wear point.
I plan to siphon out what I can and put some Shell Vpower in there to clean it up. Any other suggestions?
Thanks!

 

Very unlikely this is from using unleaded 88. 2012 RX shouldn't have any issues running unleaded 88.

 

Very lucky number 6 (easy to get at). Swap coil with number 4 and see if code follows coil. If not, swap plugs, etc...

 

I would also check your battery, if it's not very new. Low voltage can send all kinds of odd codes.

 

Battery tested good. Moved coil from 6 to 4, drove for about 8 miles, had codes checked. Still same 3 codes showing cylinder 6. Going to drive it some more in case it needs some more time/miles and I am picking up a spark plug just in case. Replacement coil comes in the mail tomorrow.

 

I think I found it - Thumbs up to Mesquite77 for helping me look in the right place - I went to put the new coil in and saw this:

Broken wire
I went back to my reference picture (right after taking off the plastic cowling and before I blew the leaves off) and it looks like 2 & 4 have had the pig tails replaced (shrink tubing) and lucky # 6 still had the original wire loom.

Coil reference pic

I did not notice that until this AM. Good thing I had not opened the coil box yet....
Picking up a pig tail this evening....

 

Sorry for the huge pics...

 

Good find. I was expecting strain relief on each wire connector. Any one else been there before and possible critter to work through the insulation?

Salim

 

After you remove that critter nest, place a few mothballs in that area before you reinstall your engine dust cover. That will usually prevent any future critters from coming back.

 

Replaced with the "guaranteed fit" Dorman ignition coil connector pigtail with crimp connectors from the local auto part chain store. The wires were a little bit larger gauge, so did not use the crimp connectors. Spliced, shrink wrapped and working fine. No more error codes. Thanks everyone!

 

Looks a lot like my critter war. It chewed off several wires that were in the way of building a nest. In the end, the critter lost the war!!

 

Yeah I'm dealing with squirrels too. They're cute but damn do they make a mess.