2003 Ford F-150 v-8, 5.4

Well my "Service Engine Soon" light is staying on. I checked my gass cap and its tight, all my fluids are filled to the max and been changed out properly. Does anyone know what would cause this light to stay on? What to look for?

Thanks!!!

 

It could be thousands of things. Go to Auto Zone, Advance Auto Parts, Oreilly, Etc.... and ask them to read your codes for you. Then post up those codes. That will help us help you alot easier!

Wayne

 

Will do tonight and get back to you. Thanks!

 

Its a P0125 error code

Autozone said its probably the thermostat.

Do I need to drain my antifreeze to replace this? Its on top of the motor. It looks loke a little will come out but thoughts?

 

If your coolant hasnt ever been changed now would be a good time to do it. I also agree its the thermostat!

Wayne

 

It was changed about 15k ago.

Should I drain my coolant to do this job?

 

I would, if you keep it clean you can reuse it.

Wayne

 

ok, thanks

 

It's usually the thermostat, but it could be a bad sensor. When warmed up, what is the temperature gauge indicating? You can use an infrared thermometer gun to see what the coolant temperature is at the thermostat. It should be around 190 F.

 

I hate to admit this but I can't remember where it used to be. I still get heat though.

I don't have access to a thermometer so I'll just go on a hunch its the t stat. At 140k its probably due for it.

How do I reset it so I can erase the service light when I'm done?

 

Disconnect the battery while you are changing it.

 

It's a "lazy" thermostat that didn't control the warmup cycle properly. It's pretty unlikely that its a sensor.

 

Well I changed out the T stat and all looks good....how can I clear out the code?

 

Did you disconnect the battery while you were changing it as I said?

 

Nope...I read this after I did the job. So I figured there might be a different way or could I just disconnect the batt still?