P2680: Coolant Degassing Valve Control Circuit High
What to do
Usually nothing to feel straight away.
If any cooling system work has been done recently — a radiator, water pump, thermostat, a hose, or just a coolant change — mention it, because two things follow from it. The connector is disturbed to get at those parts and is easily left unplugged, which is free to fix. And a system that was refilled without being properly bled or vacuum-filled is full of air, which is exactly what this valve is there to get rid of.
Ask for the plug to be checked and for the system to be properly bled. Together those two cover most of these.
What this code means
The coolant degassing valve's control circuit reads above its valid range — an open circuit, a disconnected connector, or a short to supply.
The valve's purpose is described at P2678, and the coolant-contamination warning at P2679 applies equally: an open circuit is what a corroded terminal eventually becomes.
The other timing worth noting is that this family very often appears immediately after cooling system work — a radiator, a water pump, a thermostat housing, a hose, or simply a coolant change. That is not coincidence twice over. The connector is disturbed for access, in a crowded spot at the top of the engine, and it is easy to leave unmated. And a system refilled without proper bleeding is full of exactly the air this valve exists to remove, so its first job after the work is a hard one.
A code from this family appearing after coolant work therefore wants both checks: the plug, and whether the system was properly bled or vacuum-filled. Neither costs anything, and doing the second one properly often resolves the complaint that came with the code.
Likely causes
Start here
- Disconnected sensor connector · easy
- Open circuit in module wiring · moderate
- Faulty coolant degassing valve · moderate
- Air trapped in cooling system · moderate
Less common
- Wiring shorted to voltage · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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