Code P11EC - Sent to machine shop - Now new problem!

So back in May my truck (2018 OR 4x4) with 35000 miles got a check engine light, which turned out to be the P11EC code. The Toyota Service Center told me they had to replace the head, which meant pulling the engine. I got my truck 3 weeks later and was told that the replacement head was on backorder, so they sent the head to a machine shop. I was just happy to have my truck back for a road trip we had planned.

This weekend the check engine light is back on! Brought it in and was told that they have to replace the 02 sensor, and that its NOT covered under warranty. They said that since it was in for a major service recently, they will pay for the part but I have to pay $350 for the service.

This just doesn't seem right, I am skeptical that this issue is completely unrelated to them pulling my engine.

Also it concerns me that my cylinder head was sent to a machine shop rather than being replaced with a new part. I was not even given the option for waiting on the part. I would have chosen to have my truck as it came from the factory, not machined. I personally would not want to buy a truck that has been machined to be fixed, and I think others would feel the same once I decide to sell it.

What do you guys think?

 

I hate to say it, but even the quality of machine shops these days is in the toilet. I sent a BMW head out and got it back with the valve stems all at different heights a few years ago. I should have rejected it. There was no reason for them to grind the valve stem heights.

When I installed it, it rattled like a tractor no matter how much the valves were adjusted in spec.

 

if they’re not going to warranty it, grab an OE part and throw it in there yourself. Sorry for your troubles OP, that’s frustrating.

 

What did they have to machine?

 

Apparently the exhaust valve on cyl 1 was not fully closing. Not exactly sure what they machined on the head

 

What code came up when the check engine light came on?

 

I dont know the code that came up for the 02 sensor issue.

 

I always thought o2 sensors fell under the emissions warranty

 

Imo, O2 sensors shouldn't die in 5 years.

 

When I had my engine replaced last year under warranty (Jeep, not my Tacoma) they had to replace the 02 sensor with it.

 

If that’s the case, they likely ’lapped’ the valve (if valve was damaged, replaced) they may have also shaved the head to ensure no warp/flat. Not rocket science and surprised nobody at the dealership knew how to do that. Might not have even have needed to pull the engine to do it (depends on side and clearance).

 

I wouldn't loose sleep over running a head which had been Machined by an outside source; I've done it with other vehicles with no problems. For a lot of older vehicles a Machine Shop is your only option.

That said, quality varies a lot. However I doubt a Dealership would want to risk a come-back over a poor Valve Job. You should have asked which shop they sent the Head to then researched it on your own to see what sort of work they do.

 

I worked in a machine shop that serviced a few dealers in our area. I'm on the side of the fence that the machine shop is fine provided the machine shop knows what they are doing??? Many do or they wouldn't be in business long. Some don't. Some would shortcut it and just focus on the cylinder with the issue. Hard to be 100% sure...
Our process was to >
Heads:

• disassemble and clean
• check for cracks
• check for straightness and mill if necessary
• check guides, valves, seats, springs retainers, etc.. replace as necessary (no knurling of guides!)
  
• grind seats, resurface valves, replace as necessary (
  
• reassemble with new seals as necessary

"Apparently the exhaust valve on cyl 1 was not fully closing. Not exactly sure what they machined on the head"
This probably damaged the seat, valve, and guide (exhaust valve can't dissipate heat and can damage valve and seat (beyond grind-ability).

If you can do it, change the O2 yourself. I'm sure someone here has done it with guide and possible tool needed. If not, maybe go in and ask those questions on why it went bad so early, right after major engine work, etc... nicely. Not accusing. They might help out.

 

https://www.tacomaworld.com/threads/2016-tacoma-air-fuel-sensor-replacement.559411/

 

I diagnosed countless Fords that came back after an engine repair with a check engine light. Many needed an oxygen sensor. I suspected many died due to use of impact guns hammering exhaust pipes bolts on and off. Something to consider.