Code: P0125?

[mrphdvr]

The other night while going to church, the Check engine light came on (in the wife's explorer) and the Temp Guage quit working. It made it home and I even drove it to work the next day (nothing else to drive). I plugged in the code reader and got P0125 which says this:

Insufficient Coolant Temperature for Closed Loop Fuel Control

The truck seems to ride fine and the engine is not making any funny noises. It's still the stock 4.0. Can anyone tell me what all is involved in the "Closed Loop Fuel Control".

 

[gearz]

Thermostat stuck open?

The other night while going to church, the Check engine light came on (in the wife's explorer) and the Temp Guage quit working. It made it home and I even drove it to work the next day (nothing else to drive). I plugged in the code reader and got P0125 which says this:

Insufficient Coolant Temperature for Closed Loop Fuel Control

The truck seems to ride fine and the engine is not making any funny noises. It's still the stock 4.0. Can anyone tell me what all is involved in the "Closed Loop Fuel Control".

Check to see if your heater is working. My X had the same problem after the thermostat stuck open (better than being stuck closed, btw) which prevents the coolant from reaching normal operating temperature. If the coolant never warms up the computer never switches out of 'open loop' control which is kind of a warm up mode. The truck will run ok in open loop but mileage will be poor and the mixture I believe will be too rich which is not good for the engine. I suppose the code could possibly be from a broken temp sensor also but for me the thermostat replacement was the easy fix to the problem.

 

[mrphdvr]

The heater works fine. While driving it home from work on thursday the temp guage moved just a little above "C" but didn't get any higher and then it went back down. I would love for it to be something as simple as putting in a new thermostat. I bought a Clymer Manual today to do some studying on it.

 

[mrphdvr]

Still not fixed

Well I checked my Thermostat and that was good. I bought a new Engine Coolant Temp sensor and a new Sending Unit. I installed those and cleared the code. It seemed to work fine and now the "check engine" light is back on with the same code. It takes the heater a long time to start blowing hot air (20 miles plus). The gas mileage has not chaged and it drives just fine.

Can anybody give me a direction to head in from here? I'm going to start checking the wiring from the sensors.

 

[tcbradbury98]

I'm having the same code, w/ the exact same problems. My console computer also says the engine temp is fine. I am going to check the t-stat but, don't want to start replacing sensors blindly. I am also going to check the wiring for shorts. Any other ideas?

 

[BrooklynBay]

What is the temperature range of your thermostat?

 

[tcbradbury98]

I don't know, plan to check it today or tomorrow. Also my temp gauge will rarely get to even half way now, this leads me to think the t-stat is the culprit, since the temp gauge is a separate circuit from the ECT.

 

[mrphdvr]

We had to take it to a body shop anyway so we asked a friend there to have a mechanic look at it. It turned out that it was the vacuum control valve for the heater. The part was less than $3. In the 2k models it is located on the 2 hoses entering the firewall on the passenger side. I'm not sure where it is on earlier models. A friend at church with a 98 or a 97 had the same problem. It may be a common thing for trucks over 100k.

 

[tcbradbury98]

It was the t-stat, could move it w/ your finger.

 

[97FordRanger]

Does anyone have the layout of where the thermostat is located & how to remove this. Sorry but it's too much money to take in an have it fixed. 6cyl 4.0l
Thank you in advance.