P0125 Fault Code

Insufficient Coolant Temperature for Closed Loop Fuel Control

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0125 fault code indicates that the Engine Control Module (ECM) has detected insufficient coolant temperature for closed loop fuel control. Essentially, the ECM relies on the coolant temperature to optimize engine performance and emissions. If the temperature does not reach the expected level, it can lead to inefficient combustion and increased emissions.

What are the symptoms of the P0125 code?

• Check Engine Light illuminated on the dashboard
• Poor fuel economy due to imprecise fuel mapping
• Engine performance issues, such as lack of power or rough idling
• Emissions possibly exceeding standards, which may cause issues during inspections.

What causes the P0125 code?

• Low coolant level due to leaks or insufficient refill
• Faulty thermostat that is stuck open
• Defective coolant temperature sensor, causing inaccurate readings
• Wiring issues leading to faulty communication between the sensor and ECM
• Problems with the engine’s heating system, not allowing it to reach the correct temperature.

How to fix P0125?

• Inspect and refill coolant to the proper level
• Replace a faulty thermostat to ensure it closes properly and holds coolant until the engine warms up
• Test and replace the coolant temperature sensor if it's not providing accurate readings
• Check the wiring and connectors for damage or corrosion, repairing or replacing as necessary
• Make sure the engine's heating components are functioning properly.