Cause
Air trapped in cooling system
An air pocket left after cooling system work, or drawn in by a leak. Air where the temperature sensor sits makes it read the air rather than the metal, so the gauge can look normal while the engine overheats — and a heater that blows cold with a full expansion tank is the classic sign, because the matrix is the highest point in the circuit.
This code after any cooling work is an incomplete bleed until proven otherwise.
Typically a moderate job.
Some of these codes mean you should stop driving
1 of the 9 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (9)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2680 Coolant Degassing Valve Control Circuit High Likely for this code Moderate
- P0116 Engine Coolant Temperature Sensor 1 Circuit Range/Performance Moderate
- P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control Moderate
- P0126 Insufficient Coolant Temperature for Stable Operation Moderate
- P0217 Engine Coolant Over Temperature Condition Stop driving Critical
- P0483 Cooling Fan Rationality Check High
- P2183 Engine Coolant Temperature Sensor 2 Circuit Range/Performance Moderate
- P2457 Exhaust Gas Recirculation Cooler A Efficiency Below Threshold Moderate
- P2678 Coolant Degassing Valve Control Circuit/Open Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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