2007 Tacoma misfiring, multiple codes O2 sensor

Let me begin by saying I have been wanting a Tacoma for several years and I finally had the opportunity to purchase one at a reasonable price for a nice vehicle...

I bought a 2007 Tacoma from a local dealer, the check engine light was on when I purchased it but I had it checked out and it pulled codes for an O2 sensor and they replaced with an aftermarket part. 10 minutes after leaving the lot the light was back on. Yesterday the truck started misfiring (shuddering) in low RPMs and in 1st/2nd gear it seemed. As it was having this problem the check engine light was flashing (I've read multiple threads and this is a signal for misfires). I could turn off the truck and restart it once warm and it didn't shudder anymore but the light was still on constantly.

Today I take the truck down to the Toyota service department per request of my dealer that I purchased the truck from and shows the following codes: p0157 p0158 p0300 p0306 p0606
So O2 sensor, random misfire, cylinder 6 and ecm. I know what they are but I am not a mechanic nor extremely mechanically inclined around an engine.

Additionally after leaving the dealership today the truck didn't want to turn over but finally did after multiple attempts. No click or anything then 3-4 times later cranked and cranked then started So I took it right back and left it. Once again the bill isn't going to be on me anyway.

They are going to keep it and fix the O2 sensor first then work from there. This isn't on my dime, it's on the dealership since it was an existing problem. Toyota pulled the service log of the truck and it had a head gasket replaced at 50k and again at 122k miles. It sits at 133k miles today, so keeping fingers crossed this isn't a lemon of an engine.

This is all the information I have, I read other threads thoroughly and I haven't seen anyone with all of the same codes going off that I have right now and although I love the purchase I'm wondering if I should take this back to the dealership and find a replacement. Thoughts, questions, concerns and help is asked and warranted. Thanks

 

Btt

 

It sounds to me like a blown head gasket. It could be that the head to block mating surfaces may not have been machined properly during the previous replacements.

Sorry, but all indications point in that direction. At least it is on their dime and not yours.

 

The only thing that leads me to believe that it may not be the head gasket is that it's not an "all the time" issue and after it warms up it doesn't have the same issues. Maybe I'm wrong, honestly just don't want that vehicle to be in the shop for an extended amount of time. Hopefully the problem is resolved quickly or at least they find out more tomorrow after the O2 sensor is replaced.

 

The O2 sensor is more than likely fine. The O2 Sensor code is probably due to the misfiring cylinder 6.

I hate being a negative Nancy, but ...

I hope you are correct in your belief...

 

Regardless of the problem at least I'm not out of pocket, I just hope it's not ominous for my vehicles future.

 

Just to update for those that may be having similar issues it is indeed a head gasket. The dealership is fixing it at no cost with a certified Toyota mechanic and a one year parts warranty on the fix. Here's hoping this issue doesn't arise again, guess I'll be without my new (to me) truck for a couple weeks but at least the problems will be resolved.

On a side note I'm very surprised that a Toyota engine has had a history of problems like this. The mechanics that are working on the engine know of it and are going to determine exactly why this has been an issue. They think the gasket was poorly machined and that's what caused multiple problems, fortunately our local machine shop builds VERY expensive high performance racing engines for several different companies (including Toyota) and I trust them completely with the gasket. (Cornetts Machine Shop in Somerset KY for those interested)

 

There was an identified issue with defective head gaskets that was replaced using a new designed gasket. The last time the gasket was replaced they may have used an older defective designed gasket.

Best of luck!

Jimmyh