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Car Forum / Ford / Ford Explorer / December 200697 Explorer 5.0 with P0125 Code
This shows a generic code for "Insufficient Coolant Temperature for Closed Loop Fuel Control". Does anyone have an idea which sensor would cause this code? Is it the engine temperature sensor C159 on the radiator? Maybe the engine coolant temperature sensor on the engine C163? Could this be a computer problem? Any help would be appreciated, I have been chasing this for a couple months. I reset the CEL and it's fine for a week or two then it comes back. Is the engine coming up to operating temp? Perhaps it needs a new thermostat... > This shows a generic code for "Insufficient Coolant Temperature for > Closed Loop Fuel Control". Does anyone have an idea which sensor [quoted text clipped - 3 lines] > appreciated, I have been chasing this for a couple months. I reset > the CEL and it's fine for a week or two then it comes back. The engine seems to be warming to a normal operating temperature >Is the engine coming up to operating temp? Perhaps it needs a new >thermostat... [quoted text clipped - 6 lines] >> appreciated, I have been chasing this for a couple months. I reset >> the CEL and it's fine for a week or two then it comes back. To be honest, you really need to be a little more sure than "seems".... While it is possible that the ECT is faulty, it is rare that these sensors require replacement. These sensors are a simple thermistor and there's not much that can go wrong with them. I'll probably replace it just to be sure that it is not the problem . The needle on the instrument panel shows middle of the gauge. The radiator shows 200 F on a IR thermometer. Could it be a bad ground or a broken wire to one of the sensors? >To be honest, you really need to be a little more sure than "seems".... >While it is possible that the ECT is faulty, it is rare that these sensors >require replacement. These sensors are a simple thermistor and there's not >much that can go wrong with them. OK.... info is our friend... The ECT and the (IIRC) IAT both share the same line for VREF.... about 4.5 or 5 volts. Since these thermistors react inversely, cooler = higher resistance..... If your IR thermometer shows 200F when you point it at the thermostat housing, you can unplug the ECT and measure the resistance across the two pins.... Expect in the neighbourhood of 2.5K ohms - give or take. If this is good, suspect corroded or spead terminals in the wiring connectors.... <aybe wiring concerns if someone has been in there poking and prodding... I would expect there to be (at least) three connectors in the circuit.... one at the PCM, one at the sensor and another where the engine harness and the chassis harness meet. You couls also use your DMM to back probe the sensor terminals while the connector is connected and the engine is running. Measure between the VREF terminal and the battery ground should give the 4.5 to 5 volt indication.... sig return will depend on engine temp.... operating range is about 0.3 volt to about 3.5 volt - at 200ish degrees, expect something around a half volt.... FWIW, this type of circuit is a "voltage divider" type circuit... If you are unfamiliar (this is not intended as an insult), you can Google the term and should find some pretty good explanations of the concept... Thanks...you have given me something to work with. I will have to Google the "voltage divider as I am not familar. I'll let you know what turns out to be the problem. >OK.... info is our friend... The ECT and the (IIRC) IAT both share the same >line for VREF.... about 4.5 or 5 volts. Since these thermistors react [quoted text clipped - 17 lines] >unfamiliar (this is not intended as an insult), you can Google the term and >should find some pretty good explanations of the concept... Jim...your original diagnosis of the bad themostat was correct. When I got it out, it would not close completely and didn't allowed the antifreeze to warmup. I live in Phoenix and until a couple weeks ago we had warm weather, so the stuck themostat wasn't apparent. Great Job! >Thanks...you have given me something to work with. I will have to >Google the "voltage divider as I am not familar. I'll let you know [quoted text clipped - 21 lines] >>unfamiliar (this is not intended as an insult), you can Google the term and >>should find some pretty good explanations of the concept... |
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