Engine Overheated, Now Engine Won't Start - p0115 Code??

[Internut]

I recently bought a 2000 Toyota MR2, 5 speed, with 61K miles. So I was driving on the highway going about 65 mph and the check engine light came on so I began to inspect the guages. The engine seemed to start to run a bit sluggishly and acceleration/power seemed to be missing. I then noticed that the engine seemed to have higher pitch to it. This all happened within 2 minutes of the check engine light coming on so I immediately pulled over in the breakdown lane.

I noticed that the engine was off as I was pulling over but I am not certain when the car actually died because I was trying to get to the breakdown lane. Once I got the to breakdown lane and stopped I began to smell coolant so I looked down at the gauges and noticed the Temp gauge was pegged. Some steam was now coming out from the rear engine compartment. After letting the car site I tried to start the car and sure enough it would not start.

I had no other issues with the car before this, overheating or otherwise. I have had the car for about 1 month. I had the car towed to my brothers and we got a Code Reader and the code P0115 came up - Engine Coolant Temperature Circuit Malfunction. So we replaced the ETC (engine temp control), part from Autozone. Refilled some coolant. Coolant was down about 1 gallon of 50/50 mix. I am not sure how much the whole system takes.

Replacing the ETC didn't fix the problem. I cleared the code as well to make sure there wasn't some fail safe preventing the car from starting.

I am not sure what to do now or if I just replaced the wrong part. I am wondering if I have a timing belt issue...

Any help would be great.

Thanks,

Scott

[ModifierMR]

It sounds almost certainly that you blew the head-gasket on the motor.

The head gasket is a thick metal/rubber/composite material sits between the head and engine block. It keeps coolant, oil passages and cylinders all separate from each other. If your engine overheats to the point of no return it will cause a breach between the coolant and oil, or cylinder bores, causing the car to burn massive amounts of coolant. This will also cause the car to have lower compression and cause it to run poorly and not at all.

I would drain your oil and check the consistency of the oil, make sure it does not have any milky residue in the oil and is clear of any water. If you were running the engine this way for awhile without realizing it, you could have caused severe damage to the bottom-end internals which may explain the high-pitch noise you heard.

however, your thought about the timing belt is very plausable as well, but because the car didnt die while driving and you shut the car off when you came to a stop, I would say check your compression and oil first and make sure the headgasket is not to blame.

[Jason.MZW20]

Well the 1ZZ doesn't use a timing belt, it uses a timing chain. However, the water pump (and all other accessories) is driven by a serpentine belt, IIRC.

More than likely the engine has warped and the head gasket blew. Aluminum blocks don't take kindly to being overheated. The fact that it will no longer start probably means you lost compression in 2 or more cylinders. The engine could limp on 3 cylinders, but not 2.

BTW, Toyota ECUs initiate timing retard above about 220*F, so that explains your loss of power under load as it was likely already overheating. At idle, the ECU will move to advanced timing (to raise the idle and improve coolant flow), which can cause the engine to stall. At roughly 240*F, maximum timing retard is used under load and maximum timing advance at idle.