I just installed a new coolant temperature sensor on my 2012 Escape 3.0V6 and the 'check engine' light went away (after disconnecting the battery to reboot the computers), but it is still failing CA smog inspection. The tech says he's still getting the 'bad thermostat' code, but there is nothing wrong with the cooling system. I was told to drive the vehicle up to 15x from a cold start to freeway temps before returning for a retest (which sounds ridiculous). Does anyone know if this could be the thermostat being stuck open? Or is it the computer (or sensor)? Because the vehicle runs like a top and stays below half way to hot even during stop-and-go driving & on the freeway so I would really prefer not have to do any repairs. Even if replacing the thermostat is a simple job I've done many times. Do I really need to do all that driving on the freeway (and waste all that time & gas)?

 

What is the specific code that is being reported out? There are multiple codes for the cooling system so trying to guess which one could waste your time as well as ours.

The "drive the vehicle...before returning for a retest" is to complete a drive cycle. The I/M Readiness codes will not be cleared until a drive cycle is completed, and the emissions locations are unable to perform their tests if the I/M Readiness code is present.

I would not count on disconnecting the battery to clear stored diagnostic codes. You're going to be better off using a proper scan tool to read and clear codes. There's so much inconsistent and even incorrect information floating around on the effectiveness of disconnecting the battery on modern OBD-II systems that I don't know if anyone really knows what's accurate now.

-Rod

 

The code from my local auto parts company's reader was not revealed. They just said it's a 'Thermostat' issue. I'll see if the Smog Test tech will share the code with me.

In the meantime - is it normal to ask an owner to drive the vehicle as many as 15 times from a cold start to freeway temperature before he re-tests the system? And why in the golden State of California is an engine cooling problem (which I don't have, except for perhaps a thermostat stuck open) now part of a SMOG TEST? In that case they should call it the EVERYTHING TEST!

Thanks for the assist!

 

As mentioned in post #2 above, asking the owner to drive the vehicle is to complete the drive cycle. Disconnecting the battery may have reset the drive cycle and until that is completed, the smog test cannot be performed. The smog technician is just giving you the "simple answer" but if you want to understand more fully what you need to do before he can perform his test, you can find those details here: https://www.ford-trucks.com/forums/a...6&d=1707023680

-Rod

 

Thank you. What I need to know is the '15 drive cycles' a normal amount (for recalibrating the computers)? If not, will fewer cycles be able to do the trick? In the meantime should I replace the thermostat or wait until the computer recalibrates itself? I don't want to have to do the mechanical fix unnecessarily. Especially if it messes with the recalibration. Thanks!

 

Did you take a look at the link I provided in Post #4 above?

If you don't know what the specific code is and your engine gets up to operating temperature and remains there fine, I would not just blindly replace the thermostat.

-Rod

 

If the stored codes are erased, another code will be set indicating that all the 'normal background tests' have not been completed. That code will go away after all the tests have run. Some require a fuel tank less than half full for the Evaporative Control system, others require full warmup, park for a while, restart, and a drive at freeway speeds. Once all tests are completed without problem, the 'tests incomplete' code will go away, and the vehicle can then go the the SMOG station for a re-test.
The suggestion for 15X was intended to insure you got all the tests complete before returning by doin various tasks encountered in 15 separate trips. 15 was as arbitrary as 13 or 16 ...
A thermostat my do two things to cause an faill indication, by its natural capabilities: fail to open and cause overheating, open too soon or all the time, causing a low coolant temperature. It can also be partialy stuck open which could cause slow response getting to operating temperature. The latter is the one most likely being tagged by the OBD-II tests. To keep emissions to a minimum, the engine should reach operating temperature within xx minutes of startup. The 3.0 has a 18xF thermostat. I do not remember, but it is NOT 195 which was the norm for a lot of engines. I have not checked the cost or ease of replacing the thermostat, but if not expensive, doing that before taking all those 'trips' might insure you do not ring up a code for 'thermostat problems'.
You could invest in an inexpensive code reader and pull codes yourself. HF has readers less than $20 I believe.
Or you could purchase a OBD-II interface and connect to a PC and use FORSCAN software to pull codes. AND read a lot of hidden data if so inclined.
Given it reaches the middle of the gauge, it is likely a slow heatup time problem, but I am just guessing from the other side of the USA.
tom

 

The thermostat on the 3.0L Duratech is not too bad to do, but a lot of pieces that need to be twidled with to replace it are plastic and prone to breaking after this number of years. I'm not positive how similar the 3.0L in the 2012 is to the 2004 that I have more experience with. I'd really suggest understanding the actual code before even going to that amount of effort. Depending on the tech who reported the issue, I could see them interpreting a Cylinder Head Temperature Out of Range code, a Coolant Temperature Sensor range code, or maybe even an Intake Air Temperature sensor-related code as a "bad thermostat."

-Rod

 

Thanks Tom! I have followed your advise and replaced the thermostat. With that and the new sensor hopefully that should allow the vehicle to pass the 'Everything Test' (my new term for the smog test ). I also like the code reader adapter for the laptop (OBD-II). I'm not much of a mechanic but it would be great for verifying whatever the mechanic gets on their readouts.

Again thanks for your time and detailed explanation about the 'everything test'.

It's not as simple as the old probe up the pipe days, eh?

Happy trails,

Bob

 

SUCCESS! Passed the Everything Test! Only had to replace the thermostat. Turns out the gasket on the old one was installed under not around the disk holding the thermostat in place and it got caught in the spring locking it in the open position. The sensors use the coolant temperature to regulate the fuel mixture so that's all it was. The damned $12 thermostat!

Thanks to every on of you who chimed in with your suggestions. Much of it over my head but vastly appreciated.

Glad the 1st (and cheapest) fix did the trick!

Before I let you go, does anyone have any advice on the use of the 'Fuel Synch' plug-in fuel saving device? Does it work? It probably will mess with the fuel mixture, but if it works I don't mind because I just passed the smog test anyways. But it you don't think I should give it a try FOR ANY REASON....I WON'T!

 

Gimmick/scam device, at most it will have a few lights on it and you'll change your driving behavior to save fuel while the device actually does absolutely nothing else.. They always pop up in when gas prices spike. Don't waste your money.

 

... What he said.... I would add that it seems the factory would jump on ANYTHING that would increase fuel economy. They fall all over themself to gain a .1 or .2 increase in MPG. The Auto Start Stop mechanism is not free, the improved starter brushes and bearings is not done without spending some dollars, and all for a .1/.2 increase in fleed mpg.
I think they would have used any and all devices they could find, scouring the market for even the 'far out' oddities, and apparently they did not use this one...
I would note that some FoMoCo products have a setting that enables/disables the 'economy coach' of some sort. It will display hints on the cluster to help you improve your driving skills in
the area of fuel consumption. It is not a 'device', but encourages the driver to accelerate reasonabley, coast to upcoming stops, and use the brake pedal less. At least that's what I think
it does.
Anyway, check around to see if there's a 'coach' available by enabling using tools such as FORSCAN. I know for sure it is available on some Maverick models. Not sure if all.
tom

 

Awesome, glad to hear it was an easy fix, and even better when you find the smoking gun to help confirm it was a fix. I really dislike when things start working and I didn't find something to explain why.

As for the marketed fuel saving devices, what the two folks above said is completely right on. There have been a few YouTubers that have disassembled a variety of these types of devices and in all cases, they do not even connect to the datalines of the OBDII port, meaning they cannot possibly do anything measurable. The only ones that have a hope of doing something (other than causing you to change your driving habits) have a large and small capacitor in them in an attempt to filter some electrical noise to help sensors have a cleaner signal. But pretty much all sensors use an internally regulated voltage source from the PCM, and that regulation circuitry will include the appropriate filtering anyway for the sensors. Save you money and don't fall for the gimick.

-Rod

 

Thanks for the review! I'll save my money.

 

Thanks for the explanation (and the driver psychology). I'll be easy on the accelerator and not wasting my $ on some gimmick. Safe travels!