Insufficient Coolant Temperature for Closed Loop Fuel Control
28 articles · 3 makes affected
What is P0125?
P0125 is a powertrain code indicating your engine's coolant isn't reaching the proper temperature for the computer to switch to efficient 'closed-loop' fuel control. This is a high-severity issue that can cause poor fuel economy, increased emissions, and potential engine damage if ignored. Based on real data, it's most frequently reported in Toyota Tacoma and 4Runner models.
Common Causes
- ●Faulty engine coolant temperature sensor (most common cause)
- ●Thermostat stuck open preventing proper engine warm-up
- ●Low coolant level or air in the cooling system
- ●Wiring or connector issues in the coolant temperature circuit
Symptoms You May Notice
- ●Check Engine light illuminated (primary symptom)
- ●Poor fuel economy due to rich fuel mixture
- ●Rough idle or engine running poorly
- ●Engine takes too long to warm up
- ●Heater not producing adequate heat
How to Fix It
- ●Replace engine coolant temperature sensor ($50-$150, moderate difficulty)
- ●Replace thermostat and coolant ($100-$300, moderate difficulty)
- ●Diagnose and repair wiring/connector issues ($80-$200, moderate difficulty)
- ●Professional diagnosis at repair shop ($100-$200, easy)
Owner Statistics
Based on 68,256 real owner discussions • 2021 confirmed solutions
About This Data
Statistics are aggregated from real owner discussions on Reddit, automotive forums, and YouTube comments. All data is anonymized and represents actual repair experiences reported by vehicle owners.
Frequently Appears With
These codes often appear together in owner reports. Check these if you see P0125.
Based on analysis of 2 owner reports where multiple codes appeared together.