* Air in the system: Even with bleeding, air pockets can remain trapped in the cooling system, especially in the upper areas. The light might be cycling on and off as the air moves around and temporarily restricts coolant flow. Try running the engine for a longer period with the cap off (but be cautious of hot coolant and steam!), and make sure you're squeezing and feeling the upper radiator hose to ensure good flow. A properly bled system will have a consistent, firm upper radiator hose that gets warm evenly when the engine is running.
* Sensor issue: The coolant level sensor itself might be faulty. It could be giving false readings even though the coolant level is actually fine. This is less likely if the light was working correctly before your work, but it's possible the process dislodged something or put stress on a connection.
* Coolant leak: While seemingly unlikely if the light was working before, you might have inadvertently created a small leak during the hose replacement. A slow leak wouldn't immediately show a drastic coolant loss, but could cause the level to drop slightly, triggering the sensor. Carefully inspect all hose clamps, connections, and the radiator itself for any leaks – even small ones.
* Faulty gauge or wiring: There could be a problem with the low coolant light itself or the wiring leading to it. This is less likely given the light's previous function.
What to do:
1. Re-bleed the system thoroughly: Run the engine with the cap off (carefully!) for an extended period, ensuring the system is completely purged of air. You might need to add more coolant as it gets pulled in.
2. Inspect for leaks: Very carefully examine all connections and hoses for leaks.
3. Check the coolant level: Once the system is cool, verify the coolant level is within the proper range in the coolant reservoir.
4. Monitor the light: Keep an eye on the light over the next few days. If it continues to act erratically, or if you notice any leaks, you may need to seek professional help from a mechanic. They can perform a pressure test on the cooling system to detect any leaks that might be too small to see.
If the problem persists after these steps, the sensor or a wiring issue is more likely and requires professional diagnosis.
