Why does my F350 say check coolant additive?

In short: it’s a maintenance warning indicating the coolant additive level or concentration in your F-350’s cooling system is out of spec. Start by checking coolant level and for leaks, verify you’re using the correct Ford-approved coolant, and if the message persists, have the sensor or system diagnosed by a dealer.

What the warning means

Modern Ford cooling systems rely on a dedicated coolant additive package to protect the engine and keep the coolant circulating properly. The vehicle’s computer monitors the additive level and concentration, and a discrepancy or sensor fault can trigger the Check Coolant Additive message.

Common causes:

• Low coolant level in the reservoir or cooling system due to leaks or evaporation.


• Incorrect coolant type or improper mix with other coolants, reducing additive effectiveness.


• Air pockets in the cooling system from a recent service or refilling, which can skew sensor readings.


• Faulty coolant additive sensor, wiring, or module reporting the wrong status.


• Mechanical issues affecting coolant circulation (faulty water pump, stuck thermostat, clogged radiator), which can trigger additive monitoring problems.

These are the typical culprits; addressing the low level or leaks resolves most warnings. If the warning persists after correcting these issues, there may be a sensor or control module fault requiring professional service.

How to diagnose and fix

Follow these steps to verify and correct the issue while avoiding injury.

1. Let the engine cool completely, then check the coolant level in the reservoir (and the radiator, if your model allows). If the level is low, top it up with the Ford-approved coolant for your engine to the proper mark.


2. Inspect for leaks around hoses, the radiator, the reservoir, and the water pump. Look for damp patches, crusty residue, or puddles under the vehicle; repair or replace components as needed.


3. Verify you are using the correct coolant type and mix per your owner's manual. Do not mix different coolant chemistries, and follow the recommended service intervals for coolant replacement.


4. Bleed the cooling system if your year/model requires a bleed procedure after topping off or servicing, to remove air pockets that can affect readings.


5. Inspect the coolant additive sensor and its wiring for corrosion, loose connectors, or damaged harnesses. If you suspect a faulty sensor, have it diagnosed with Ford IDS or a qualified scanner.


6. Clear any stored codes with an appropriate scan tool, drive normally, and re-check whether the warning returns. If codes point to the additive circuit or sensor, pursue repair according to Ford service information.

Note: Do not open hot coolant system components. A sudden release of hot coolant can cause severe burns. If you see continuous overheating or coolant loss, stop driving and seek help.

Model-year considerations

Depending on your engine and year, Ford may use different coolant formulations and additive packages. Always consult your owner's manual for the exact coolant type, fill levels, and maintenance intervals for your F-350. If you recently serviced the cooling system, confirm the bleed and fill steps were done correctly to avoid residual air and sensor misreads.

Safety and precautions

Always allow the engine to cool before inspecting the cooling system, and wear eye protection when handling coolant. If you’re uncertain about any step, prioritize professional help to prevent injury or engine damage.

When to seek professional help

If topping up and basic checks do not extinguish the warning, or you notice persistent overheating, coolant leaks, or abnormal engine behavior, take the truck to a Ford dealer or certified mechanic. A trained technician can diagnose sensor faults, electrical wiring, or deeper cooling-system problems with specialized tools.

Summary

The “Check Coolant Additive” warning on your F-350 signals potential issues with the cooling system’s additive package. Start with a careful level check, inspect for leaks, confirm the correct coolant type and mix, and perform any required bleed procedures. If the warning remains after these steps, have a professional diagnose the sensor or control module to prevent overheating and corrosion-related damage.

Why is my truck saying check coolant additive?

A 'check coolant additive' message usually indicates low additive levels or sensor malfunction. Start by inspecting the coolant reservoir for proper additive concentration and top up if needed. Next, check the coolant additive sensor for corrosion or loose wiring, which can trigger false alerts.

What is a coolant additive for diesel?

Coolant additive for diesel engines, often called supplemental coolant additive (SCA) or diesel coolant additive (DCA), is a chemical additive mixed with the regular coolant to protect the engine from cavitation, corrosion, and scaling. These additives are especially crucial for heavy-duty diesel engines because their high pressure and vibration create small bubbles in the cylinder block that can eventually cause physical damage. The additives deplete over time, so their levels must be monitored and recharged periodically with the help of test strips.
 
This video demonstrates how to check coolant additive levels using test strips: 57sRnddieselYouTube · May 1, 2018
Key functions

• Prevents cavitation: SCAs, such as nitrates and silicates, protect the cylinder liners from the damage caused by cavitation. 
• Inhibits corrosion and scaling: Additives contain corrosion inhibitors that prevent rust and reduce mineral deposits, while some products also help to break down existing scale buildup. 
• Maintains pH levels: Some additives help maintain a stable pH level in the cooling system, which prevents corrosion. 
• Improves heat transfer: Some additives, like surfactants, reduce surface tension, allowing the coolant to make better contact with metal surfaces for more efficient heat transfer, potentially lowering operating temperature. 

How to use

• Check the concentration: Use coolant test strips to periodically check the levels of SCA in the coolant. The ideal range varies by engine, so consult your owner's manual or the test strip instructions. 
• Recharge when necessary: When the test strips indicate a low level, add the recommended amount of additive to the cooling system. Some coolants are "pre-charged" with additives, but the additives still deplete over time. 
• Follow manufacturer recommendations: Always follow the specific instructions from your engine or vehicle manufacturer. For example, Ford recommends checking and recharging SCAs on certain models at specific intervals. 
• Be careful not to over-add: Too much SCA can cause buildup of particles, which can damage the water pump or clog parts of the cooling system. 

You can watch this video to learn how to check and recharge the coolant additive in a Ford F-250: 38s1A Auto: Repair Tips & Secrets Only Mechanics KnowYouTube · Apr 8, 2019

How much coolant additive for 6.7 powerstroke?

For a 6.7L Powerstroke, the amount of coolant additive depends on the system. The primary cooling system requires 48 fl oz (1.41 L) of additive, while the secondary cooling system needs 16.0 fl oz (473 ml). It's crucial to use the correct type of additive specified by Ford, such as Motorcraft Specialty Orange Engine Coolant Revitalizer, and to check the levels with test strips, as modern Motorcraft coolant often has the necessary inhibitors already included. 
Primary cooling system

• Amount: 48 fl oz (1.41 L) 

Secondary cooling system

• Amount: 16.0 fl oz (473 ml) 

Important considerations

• Use the correct additive: Ensure you are using a coolant additive that meets Ford's specifications, such as Motorcraft Specialty Orange Engine Coolant Revitalizer (VC-12). 
• Modern coolant: Factory-fill coolants like the Motorcraft Orange coolant already contain the necessary corrosion inhibitors, so extra additive might not be needed at each service. 
• Check levels: Regularly check the coolant additive levels using test strips, especially if you are unsure or have a different coolant type. 
• Do not over-add: Adding too much additive can cause issues like particle buildup and damage to the water pump. 
• Follow maintenance schedule: Adhere to the recommended service intervals for coolant checks and changes to maintain system health. 

How to reset check coolant additive 2015 f350?

And under maintenance. I'm going to select coolant. And then I'm just going to hold the okay. Button. Until it resets. And that's all there is to it so the next time I start my car no more warning.