P0125 — Insufficient Coolant Temperature for Closed Loop Fuel Control
Category: Powertrain Severity: Low
Updated:
DTC code P0125 means: Insufficient Coolant Temperature for Closed Loop Fuel Control. It falls under the "Powertrain" category, with an estimated severity of Low. Common causes include thermostat stuck open, faulty coolant temperature sensor and low coolant level; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Thermostat stuck open
- Faulty coolant temperature sensor
- Low coolant level
- Cooling fan running constantly
Symptoms
- Engine slow to warm up
- Lukewarm cabin heat
- Higher fuel consumption
- Check engine light
How to diagnose it step by step
- Check the coolant level.
- Log warm-up time.
- Check whether the upper hose gets hot too early.
- Replace the thermostat.
How to fix it
It is almost always a stuck-open thermostat (same as P0128). Replace it and check the coolant sensor if the code returns.
Estimated repair cost
Thermostat: $150–400 installed.
Frequently asked questions
What does DTC code P0125 mean?
Insufficient Coolant Temperature for Closed Loop Fuel Control.
Is code P0125 serious?
Severity Low. Usually a minor fault; check the causes listed.
Can I keep driving with code P0125?
Yes, you can drive; the engine uses a bit more fuel.
Related codes
P0123 P0122 P0128 P0121 P0120 P0130 P0131 P0118 P0132 P0117
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