AutoCodes – Subaru – P0125 Subaru

P0125 Subaru Code - Insufficient Coolant Temperature for Closed Loop Fuel Control

Quick Answer

The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. Common causes include Low engine coolant level, Leaking or stuck open thermostat, Faulty Engine Coolant Temperature (ECT) sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0125 Subaru indicates Insufficient Coolant Temperature for Closed Loop Fuel Control.
Common causes: Common causes include Low engine coolant level, Leaking or stuck open thermostat, Faulty Engine Coolant Temperature (ECT) sensor.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 9,205

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0125 Subaru Description

The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Engine Control Module (ECM). The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.

OBDII Code P0125 Subaru - Insufficient Coolant Temperature for Closed Loop Fuel Control - AutoCodes.com — P0125 Subaru Code - Insufficient Coolant Temperature for Closed Loop Fuel Control

What does this mean?

What are the Possible Causes of the DTC P0125 Subaru?

Low engine coolant level
Leaking or stuck open thermostat
Faulty Engine Coolant Temperature (ECT) sensor
Engine Coolant Temperature (ECT) sensor harness is open or shorted
Engine Coolant Temperature (ECT) sensor electrical circuit poor connection

How to Fix the DTC P0125 Subaru?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0125 Subaru code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0125 Subaru code?

Need more information on how to fix the P0125 Subaru code? Get Access to Factory Service Manuals

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0125 Subaru Code

What does the OBDII code P0125 mean on a Subaru?

P0125 indicates that the engine coolant temperature is not reaching the required level for the engine to enter closed-loop fuel control.

What are the common symptoms of code P0125 in a Subaru?

Symptoms may include poor fuel economy, rough idling, a longer warm-up period, reduced heater performance, and an illuminated check engine light.

What causes the P0125 code to appear on a Subaru?

Common causes include a stuck-open thermostat, low coolant levels, a faulty coolant temperature sensor, or wiring issues related to the sensor.

Can a failing thermostat trigger the P0125 code?

Yes, a thermostat stuck open can prevent the engine from reaching the proper operating temperature, causing the P0125 code.

How do I diagnose the P0125 code on a Subaru?

Start by checking the coolant level, inspect the thermostat for proper operation, test the coolant temperature sensor, and check related wiring and connectors for damage.

Can I drive my Subaru with a P0125 code?

While the car may still be drivable, ignoring the code can lead to poor fuel efficiency and potential long-term engine damage if the issue is not resolved.

How can I fix the P0125 code on my Subaru?

Common fixes include replacing a faulty thermostat, topping off or replacing coolant, repairing wiring issues, or replacing the engine coolant temperature sensor.

Does cold weather cause the P0125 code on a Subaru?

Cold weather can exacerbate issues like a stuck-open thermostat, but it is not the sole cause of the P0125 code.

How much does it cost to repair the P0125 code on a Subaru?

Costs can vary depending on the repair, but replacing a thermostat typically costs $150-$300, while a coolant temperature sensor replacement may cost $100-$250.

What happens if I ignore the P0125 code on my Subaru?

Ignoring the code can lead to continued poor fuel economy, increased emissions, and potential overheating or damage to the engine over time.