Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU2012IMPREZA WRX STI F4-2.5L DOHC TURBOREPAIR AND DIAGNOSISA L L DIAGNOSTIC TROUBLE CODES ( DTC )TESTING AND INSPECTIONDIAGNOSTIC TROUBLE CODE DESCRIPTIONSDIAGNOSTIC TROUBLE CODE (DTC) DETECTING CRITERIAP CODESP0125
2012 Subaru Impreza WRX STI F4-2.5L DOHC Turbo
P0125
2012 Subaru Impreza WRX STI F4-2.5L DOHC TurboSECTION P0125
DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL
1. OUTLINE OF DIAGNOSIS
Detect the malfunction of engine coolant temperature output property.
Judge as NG when the engine coolant temperature does not rise in driving conditions where it should.
2. COMPONENT DESCRIPTION
3. ENABLE CONDITIONS
4. GENERAL DRIVING CYCLE
Perform the diagnosis only once after engine start.
5. DIAGNOSTIC METHOD
- Abnormality Judgment
Judge as NG if the criteria below are met.
Timer for diagnosis after engine start
a. Timer stop at fuel cut
b. During the driving conditions except a) above, timer counts up as follows.
64 ms + TWCNT ms (when at 64 ms)
TWCNT is defined as follows,
TWCNT = 0 at idle switch ON,
TWCNT show on the following table at idle switch OFF.
Judgment value of timer after engine starting
t = 451056 ms - 25870 ms x Ti
Ti : The lowest coolant temperature after engine start
Time Needed for Diagnosis: Less than 1 second
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
- Normality Judgment
Judge as OK and clear the NG when the malfunction criteria below are met.
Time Needed for Diagnosis: Less than 1 second
1. OUTLINE OF DIAGNOSIS
Detect the malfunction of engine coolant temperature output property.
Judge as NG when the engine coolant temperature does not rise in driving conditions where it should.
2. COMPONENT DESCRIPTION
3. ENABLE CONDITIONS
4. GENERAL DRIVING CYCLE
Perform the diagnosis only once after engine start.
5. DIAGNOSTIC METHOD
- Abnormality Judgment
Judge as NG if the criteria below are met.
Timer for diagnosis after engine start
a. Timer stop at fuel cut
b. During the driving conditions except a) above, timer counts up as follows.
64 ms + TWCNT ms (when at 64 ms)
TWCNT is defined as follows,
TWCNT = 0 at idle switch ON,
TWCNT show on the following table at idle switch OFF.
Judgment value of timer after engine starting
t = 451056 ms - 25870 ms x Ti
Ti : The lowest coolant temperature after engine start
Time Needed for Diagnosis: Less than 1 second
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
- Normality Judgment
Judge as OK and clear the NG when the malfunction criteria below are met.
Time Needed for Diagnosis: Less than 1 second
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.