P0125 on Toyota Vitz (SCP10): Coolant temperature too low for closed-loop fuel control

Short answer: P0125 means “Coolant temperature too low for closed-loop fuel control”. The car’s computer has found a fault in the Engine - ECT system and turns on the High coolant temperature light. First check: check thermostat.

Code

P0125

System

Engine - ECT

Dashboard light

High coolant temperature light · Check engine light (MIL) · Low coolant temperature light (blue)

Also sold as

Toyota Yaris, Toyota Echo (XP10)

Applies to

1SZ-FE (by platform)

Confidence

medium (Toyota Echo 1999–2002 factory diagnostics, same XP10 platform; not confirmed on JDM 1SZ-FE)

Source

carmanualsclub.com

Likely causes

1. Thermostat stuck open
2. Coolant temperature sensor
3. Oxygen sensor circuit

What to check, in order

1. Check thermostat
2. Check coolant temperature sensor
3. Check oxygen sensor

Related on this car

• All fault codes for this car
• Warning lights
• Where the parts are (parts map)
• Common problems

Same code on other cars

• P0125 · Toyota Corolla (11th gen, E170)
• P0125 · Toyota Corolla (10th gen, E140)
• P0125 · Honda City (5th gen, GM2)
• P0125 · Honda Civic (10th gen, FC)
• P0125 · Suzuki Wagon R (Pakistan, K10B)
• P0125 on all cars compared

← P0121 P0130/21 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.