P0128 code

[Jim Vaccaro]

I have a 185 T stat and got a check engine light.....Engine Temp Code

 

[stkjock]

P0128 OBD-II Trouble Code

Technical Description

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
What does that mean?

This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125
In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.
Symptoms

You will likely not notice any drivability problems other than the MIL illumination.
Causes

A code P0128 may mean that one or more of the following has happened:

• Low engine coolant level
• Leaking or stuck open thermostat
• Faulty cooling fan (running too much)
• Faulty coolant temperature (ECT) sensor
• Faulty intake air temperature (IAT) sensor

Possible Solutions

Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:

• Verify coolant strength & level
• Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
• Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
• Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
• If the above items check out good, replace the thermostat

 

[Jim Vaccaro]

Car runs at 185 to 190..with cooler air now it just takes too long to heat up..I will also try letting her warm up a bit longer before driving,,,I want to keep my 185 T stat..It helps keep it cooler in summer heat..

 

[Black 5.0]

Well, there is your answer. You're running a cooler thermostat. Personally, your reason for running one cooler is kind of silly. Engine temps are rarely effected by outside temperatures. The coolant remains at the same or close to the same normal operating temp even if it's 110 degrees. Vehicle abuse though, would cause it to run higher.

 

[Limetime]

Silly kids, remember your motor needs that proper heat to make power.

 

[Sky Render]

Car runs at 185 to 190..with cooler air now it just takes too long to heat up..I will also try letting her warm up a bit longer before driving,,,I want to keep my 185 T stat..It helps keep it cooler in summer heat..

As others have said: no, it doesn't. Ford tested these vehicles in more extreme conditions than you probably subject yours to. So unless you're making some crazy amount of horsepower, put the stock thermostat back on.

 

[chuck@evoperform]

I have a 185 T stat and got a check engine light.....Engine Temp Code

Why would you put a hotter thermostat in? The stock one is 180.....

 

[Jim Vaccaro]

Why would you put a hotter thermostat in? The stock one is 180.....

my bad It is a 170 T Stat

 

[chuck@evoperform]

Oh ok. Did you get the tune modified for the new thermostat?

 

[VTXFrank]

Someone is gonna be replacing his spark plugs sooner than expected. No reason to put a cooler T-Stat in these cars.

 

[chuck@evoperform]

Someone is gonna be replacing his spark plugs sooner than expected. No reason to put a cooler T-Stat in these cars.

Actually, in certain cases there is..............

 

[Jim Vaccaro]

Oh ok. Did you get the tune modified for the new thermostat?

The tuner has now did some adjusting and cleared the code,,I think he changed the warm up time....so far so good

 

[chuck@evoperform]

Did he actually make adjustments, or just disable the CEL for that particular code? And what form of FI are you planning on going to.

 

[Jim Vaccaro]

Did he actually make adjustments, or just disable the CEL for that particular code? And what form of FI are you planning on going to.

He said he made adjustment to add time for warm up..Form of FI ??

 

[chuck@evoperform]

FI--forced induction, turbo, supercharger, nitrous. That's the only reason you would need a lower temp thermostat, unless you drive in an extremely hot environment. We've only ever used the 170 degree thermostat on one 5.0 since they hit the streets last year, and that was on an 800 hp street car that was showing coolant temps in the 200's after hot lapping it at the drag strip causing it to pull timing.

 

[Jim Vaccaro]

By the way!!!

I called the Vendor where i bought the T stat and was told no one had reported this problem as yet!!!

FI--forced induction, turbo, supercharger, nitrous. That's the only reason you would need a lower temp thermostat, unless you drive in an extremely hot environment. We've only ever used the 170 degree thermostat on one 5.0 since they hit the streets last year, and that was on an 800 hp street car that was showing coolant temps in the 200's after hot lapping it at the drag strip causing it to pull timing.

I am N/A ,,no decision on power adder as yet..I want to run 11.50 index and hot lapping at times has pulled timming

 

[chuck@evoperform]

Hmmmm. Hope your timing isn't too aggressive there. I was hot lapping one night and was pretty consistent in the mid 12's (literally making the run, grabbing slip, pull right back into burnout box, doesn't happen like that too often though)

 

[rford426]

By the way!!!

I called the Vendor where i bought the T stat and was told no one had reported this problem as yet!!!

Whose the vendor reicshe?

There are plenty of reasons to run a cooler thermostat in these cars as ling as the fan settings are adjusted you will are a big improvement in cooling

 

[Jim Vaccaro]

Whose the vendor reicshe?

There are plenty of reasons to run a cooler thermostat in these cars as ling as the fan settings are adjusted you will are a big improvement in cooling

I have temp gauge and fan comes on @ 190 runs a minute or 2 and goes off on a cool day , on hotter days fan runs longer..without this T stat car ran up to 202 to 204 now with 170 T stat it runs between 185 and 192...

 

[Rob72]

Could running a cooler thermostat possibly prevent #8 issues?