Why does my Ford say check coolant additive?
The message typically means the coolant additive package is out of spec or the system detects a condition that needs attention. It can be triggered by a low coolant level, an incorrect coolant or additive mix, or a sensor fault. The fix can range from a simple top-up to a diagnostic at a dealership.
What the message means
The Ford engine cooling system relies on a protective additive package to prevent corrosion and scale. When the vehicle’s computer detects that the additive concentration, level, or condition isn’t within specification, it flags “Check Coolant Additive.” This isn’t an immediate mechanical failure, but it is a sign that the cooling system should be checked to prevent overheating or long-term damage.
The following list covers the most common reasons this alert appears.
- Low coolant level or a detected leak in hoses, radiator, or water pump.
- Incorrect coolant type or concentration mixed in the system (for example, using a coolant not approved by Ford or mixing incompatible formulas).
- Additive life has degraded over time; coolant and its corrosion inhibitors can wear out.
- Faulty coolant level or condition sensor, or damaged wiring in the cooling-system monitoring circuit.
- Air pockets in the cooling system after a refill or service, which can fool the system’s sensors.
- Recent cooling-system work where the system wasn’t properly bled or flushed.
If you see this warning, it’s a sign to inspect the cooling system and verify the coolant and additive conditions. Ignoring it can lead to overheating or accelerated corrosion inside the engine.
What to do now
Proceed with safety in mind. The steps below help you determine whether you can address the issue yourself or need professional service.
- Park on a level surface and let the engine cool completely before touching the cooling system. Never open the radiator cap or reservoir cap while hot.
- Check the coolant reservoir level when the engine is cold. It should be between the MIN and MAX marks. If it's low, top up with the correct coolant mixture as specified in your owner’s manual, using Ford-approved coolant and distilled water if a concentrated formula is used.
- Look for visible leaks (hoses, radiator, water pump, hose clamps) and signs of a coolant stain or puddle under the vehicle. If you spot a leak, seek professional service promptly.
- Ensure you’re using the correct coolant type and concentration. Ford typically requires an OE-approved coolant (often Dex-Cool or an equivalent) and a proper 50/50 mix with distilled water unless your manual specifies otherwise. Do not mix different coolants or additives unless the manufacturer approves it.
- If the coolant level is normal but the warning remains after a short drive (and the engine stays cool), consider having the cooling system bled to remove air pockets per the manual, or have a technician perform a diagnostic on the coolant sensor and related wiring.
- If you’re not comfortable performing these checks, or if the vehicle continues to overheat, contact a Ford service center or a trusted auto shop for a diagnostic and possible coolant system service.
Addressing the issue early helps prevent overheating, which can cause more serious engine damage and higher repair costs.
When to seek professional help
Certain situations warrant prompt professional inspection rather than waiting for the warning to appear again on your own:
- The warning persists after topping up the coolant or returns soon after a reset.
- The engine overheats, you notice steam, or the temperature gauge climbs toward the red.
- There are visible leaks, sweet-smelling coolant, or white residue around hoses and clamps.
- You recently serviced the cooling system and the alert appears afterward, suggesting an air bleed or improper flush.
- Your vehicle is under warranty or you’re unsure about the correct coolant/additive specification.
In these cases, a certified Ford technician can perform a cooling-system pressure test, inspect the sensor circuitry, verify coolant type and mixture, and flush or replace coolant/additive if needed.
Understanding Ford’s approach to coolant additive
Summary
The “Check Coolant Additive” alert on a Ford signals that the coolant’s additive package may be out of spec, or there is a related condition such as low level, incorrect mix, a sensor fault, or trapped air. Start with a cold-system check: verify level, look for leaks, confirm you’re using the correct Ford-approved coolant, and bleed the system if needed. If the warning persists, or if the engine shows signs of overheating, seek professional diagnosis and service. Regular adherence to Ford’s coolant recommendations and service intervals is the best defense against this warning.
