Insufficient Coolant Temperature for Closed Loop Fuel Control
The engine is taking too long to reach the temperature needed to switch to precise, sensor-based fuel control, usually pointing to the same slow-warm-up causes as a stuck-open thermostat.
Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
Frequently asked questions
Can I drive with P0125?
In most cases, yes — P0125 is generally not an urgent safety issue and the car is usually safe to drive for a while. Still, get it checked soon, since the underlying cause can affect fuel economy or emissions the longer it's left.
How much does it cost to fix P0125?
The cost varies too much by cause and vehicle to give a single figure here — a diagnosis will narrow it down.
Code names compiled from open SAE/ISO references; explanations and repair guidance are original editorial content Last verified: 09 Jul 2026 · Our methodology