Circuit Description
The DTC P0125 Excessive Time To Closed Loop Fuel Control diagnostic monitors the relationship between running time and engine coolant temperature (ECT) sensor activity. In normal operation, the typical increase in engine temperature will allow the HO2S 1 to become active and go into Closed Loop operation soon after the engine is started.
The powertrain control module (PCM) applies 5 volts to the ECT sensor. The PCM monitors the voltage across the ECT sensor and converts the voltage into a temperature reading. The PCM will receive a high voltage input when the coolant temperature is cold, and a low voltage input when the coolant temperature is warm. If the PCM fails to detect the expected change in voltage from the ECT sensor after the engine has been running a specified number of seconds, DTC P0125 can set.
Conditions for Running the DTC
| • | DTC P0100, P0101, P0102, P0103, P0115, P0117, P0118 are not set. |
| • | The engine coolant temperature is at a specified value at engine start up. |
| • | The engine has been running for at least 120 seconds. |
| • | DTC P0125 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | Condition 1 |
| The ECT is less than -7°C (+20°F) at engine start up, and the ECT is 20°C (68°F) or less after running for 20 minutes. |
| • | Condition 2 |
| The ECT is between -7 and +10°C (+20 and +50°F) at engine start up, and the ECT is 20°C (68°F) or less after running for 5 minutes. |
| • | Condition 3 |
| The ECT is more than 10°C (50°F) at engine start up, and the ECT is less than 20°C (68°F) after running for 2 minutes. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second key cycle in which the DTC sets. |
| • | The PCM stores the conditions which were present when the DTC set as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present. |
| • | The DTC clears after 40 consecutive warm-up cycles have occurred without a fault. |
| • | A DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
Check for any of the following conditions:
| • | Check for the proper operation of the engines cooling system, including the correct coolant level. Refer to Engine Fails To Reach Normal Operating Temperature . |
| • | A faulty thermostat that stays open slightly can cause DTC P0125 to set in cold weather when the vehicle is started and let sit while warming up. Replace any suspect thermostat. |
| • | Use the Temperature vs Resistance table in order to evaluate the possibility of a shifted ECT sensor. A shifted sensor could result in DTC P0125. Refer to Temperature Versus Resistance . |
| • | Check for a faulty electrical connection to the PCM. |
An intermittent malfunction may be caused by a fault in the ECT sensor electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.
The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step checks for other DTCs that must be diagnosed first.
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This step checks for a faulty ECT sensor or ECT sensor circuit.
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This step checks the integrity of the ECT sensor input circuit.
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This step checks the integrity of the ECT sensor ground circuit.
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This step checks the integrity of the ECT sensor input circuit.
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A cooling system that prevents the engine from warming up properly and reaching the correct engine operating temperature within a set run time can cause a DTC P0125 to set. A thermostat that stays open slightly can cause a DTC P0125 to set in cold weather when the vehicle is started and let sit while warming up. Replace the thermostat if suspect .
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This step determines if DTC P0125 is the result of a hard failure or an intermittent condition.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||||||||||
Are there any DTCs set other than DTC P0116 or P0125? | -- | Go to Step 3 | ||||||||||
Is the ECT sensor value displayed near the actual coolant temperature? | -- | Go to Step 10 | Go to Step 4 | |||||||||
Does the engine coolant temperature equal the specified value? | -40°C (-40°F) | Go to Step 5 | Go to Step 8 | |||||||||
Does the engine coolant temperature equal the specified value? | 140°C (284°F) | Go to Step 12 | to Step 6 | |||||||||
Does the engine coolant temperature equal the specified value? | 140°C (284°F) | Go to Step 7 | Go to Step 8 | |||||||||
7 | Repair the open or high resistance in the ECT sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 13 | Go to Step 9 | ||||||||
8 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 9 | ||||||||
9 | Repair the faulty connection at the PCM or the ECT electrical connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 13 | -- | ||||||||
Was a repair necessary? | -- | Go to Step 13 | Go to Step 11 | |||||||||
Does DTC P0125 set? | -- | Go to Step 12 | Go to Diagnostic Aids | |||||||||
12 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Is the action complete? | -- | Go to Step 13 | -- | ||||||||
13 |
Are any DTCs displayed on scan tool? | -- | Go to Step 14 | Go to Step 2 | ||||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
