p0125-insufficient coolant temperature for closed loop fuel control

I have a 2002 lincoln ls v8 w/111k miles. Recently the engine light came on reading p0125-insufficient coolant temperature for closed loop fuel control. Engine temp reaches quater of the way up never really warms up. Sometimes it reaches the operating temp of halfway but gauge goes between half to a quater. has a hard start sometimes and recently the "check advancetrac" light comes on. im starting to have to many problems with this car so im thinking about trading or selling and want to know what the cost to fix this problem or sell "as is". Any help is appreciated?

The cost to fix the first problem mentioned is probably around $10 to $15. It is most likely that you just need to replace your thermostat. (While you are at it, you should flush your cooling system and replace the existing coolant with new.)

The check AdvanceTrac issue is more difficult to guess at with out the diagnostic codes. The generic readers won't pick up AdvanceTrac codes.

i noticed yesterday while driving home that when the heater isnt on it gets to normal operating temp but as soon as I turn on the heat the temp gauge drops

replaced thermostat fixed the problem

Replaced thermostat was a temp fix. Check engine light came on after 3 weeks with the same p0125. After replacing thermostatcheck engine light went off but after 2 weeks came back on but temp gauge and heat work fine just throwing up a code.

Also on a second note advancetrac light was the cause of a faulty new refurb alternator that a shop put on

Replaced thermostat was a temp fix. Check engine light came on after 3 weeks with the same p0125. After replacing thermostatcheck engine light went off but after 2 weeks came back on but temp gauge and heat work fine just throwing up a code.

Also on a second note advancetrac light was the cause of a faulty new refurb alternator that a shop put on

Did you put the correct 195 degree OEM thermostat in? Is the thermostat housing in good shape and holding the thermostat tightly?

i wasnt sure til i looked at the box the thermostat came in its a 186 degree or something in the 180s it wasnt a 195 replacement it was what they gave me for the car didnt know they have 2 diffrent degree therms. the housing and everything was fine. looks like i will be replacing the thermostat again this weekend. the temp gauge seems to be working fine would the 195 degree make that much of a difference throwing codes? i hoping that its not the temp sensor under the manifod. thanks

wait about that t-stat

i just checked autozone.com

the OEM stat is correct @ ~183 degrees

OE recommended temperature

Notes: 183 degrees Seal included
Gaskets Included: Yes

Material: Stainless Steel, Copper

Package Contents: Thermostat, Gasket

Thermostat Opening Temperature Rating (°F): 183

i think it's your sensor and/or wiring once you ruled out coolant leaks & burped the system of air bubbles

easy to test once you pull it off

or

if you can reach the plug while on the vehicle, to attached your ohm meter

to test for resistance when both cold (higher reading) & hot (lower reading)

http://images.wrenchead.com/smartpages/partinfo_resize/STA/TX61_FULL.JPG

i hoping that its not the temp sensor under the manifod. thanks

hmm, fom another poster:

On the intake, Near the top radiator hose inlet.

Note this model has 2,

1 Runs the gauge (you verified it was working already)

The other tells the pcm what temp the motor is for strategy (closed loop mode)

http://www.fixya.com/cars/t5069506-temp_sensor_2002_lincoln_ls_v8

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then, i got this conflicting location:

According to the factory service manual the Cylinder-head temperature sensor is located on the passenger side of the engine block, at the bottom of the number 3 cylinder intake port, (under the intake manifold). You will need to remove the intake manifold to replace it.
No wonder you can't find it...... It is also possible the wire to the sensor has melted or grounded out

http://www.lincolnsonline.com/forum/showthread.php?t=61708

wait about that t-stat

i just checked autozone.com

the OEM stat is correct @ ~183 degrees
...

I suspect that Autozone is wrong (imagine that).

The factory thermostat is 195 degrees (fully open by 220 degrees) on gen II. I think the same applies to gen I, but I'll check the factory manuals for gen I tonight to see for certain.

Of course, it's possible that the cylinder head temperature sensor is bad too.

OK, confirmed

and went to advance auto parts.com to have a totally different designed t-stat with 195 degree opening (stant style ~ seems longer than the motorcraft)

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edit: blech, rock auto.com has 3 listings...

and they have 2x 183 degree t-stat says it's OE opening (GATES, STANT)

but has a 3rd option of a 190 degree (MOTORCRAFT # RT1154) :eek7:

http://info.rockauto.com/getimage/getimage.php?imagekey=383925&imageurl=http%3A//info.rockauto.com/Motorcraft/RT1154.jpg

blah, further digging, the longer stant style is for the 6 cyl engines

http://www.partstrain.com/images/product_images/thumbs200/stant/st14139.jpg

This is from the 2002 Ford Factory Service Manual for the Lincoln LS under the diagnosis section for the thermostat. For the purpose of the thermostat test the manual does not distinguish between V6 or V8. The voltage references are wrt the the coolant temp sensor:

2002 Lincoln LS Workshop Manual

If the thermostat opening voltage is less than 2.3049 volts and less than 80°C (176°F), install a new water thermostat.



If the thermostat opening voltage is greater than 2.3049 volts 82°C (180°F), the water thermostat is good and a new water thermostat should not be installed.

-Rod

Okay, from the 2002 Ford Factory Manual, page 303-03-2:

Water thermostat start to open temperature: 87-93C (192-199F)
Water thermostat full open temperature: 104C (219F)

The thermostat test section (page 303-03-18) is as shorod indicates.

I stand by my assertion that the factory thermostat is 195F (192-199 range).