Scanline › Fault codes › Cooling
VAG 16509Insufficient coolant temperature for closed-loop fuel control
16509 is the VW Group 5-digit number VCDS (and older VAG-COM versions) shows for P0125. P0125 means “Insufficient coolant temperature for closed-loop fuel control”. It's a generic powertrain code (fuel and air metering), so it means the same on every make, including VW, Škoda, Audi, SEAT and Cupra.
- Not urgent
- SystemCooling
- TypeGeneric (same on all makes)
- VCDS number16509
How urgent is it?
Usually not urgent; often emissions-related.
Which system and module
Scanline files it under Cooling. The first letter, P, means powertrain (engine, transmission, emissions).
Usually stored by the engine control unit (VCDS address 01, Engine).
What usually causes it
- Thermostat stuck open
- coolant temperature sensor
Typical causes are a starting point, not a diagnosis of your car.
Related codes
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Open ScanlineScanline explains fault codes; it isn't a repair authority. This page explains what the code means; it can't tell you what is wrong with your car. Ross-Tech's wiki has their own notes on VW Group faults.