The P0494: Fan Speed Low code indicates that the engine cooling fan is running at a lower speed than expected. This can be caused by a faulty fan, an issue with the fan control circuit, or a low voltage supply to the fan. Low fan speed can result in insufficient cooling, which could lead to engine overheating and performance problems.
P0494 – Quick Overview
Meaning | P0494: Fan Speed Low |
Is it serious? | Yes, low fan speed can cause the engine to overheat, leading to performance issues and potential engine damage. |
Possible causes | – Faulty fan – Faulty fan control circuit – Low voltage supply |
How to diagnose? | – Test the fan for low speed issues – Inspect the fan control circuit – Check voltage supply to the fan |
P0494 Meaning
The P0494: Fan Speed Low code means that the engine cooling fan is running slower than it should, which can negatively affect the cooling system’s performance. This could be due to a faulty fan motor, problems in the fan control circuit, or inadequate voltage supply. If the fan does not operate at its proper speed, the engine might overheat, which can lead to severe engine damage if not addressed.
Step-by-step diagnostic guide
Follow the outlined procedure to diagnose this DTC by eliminating possible causes one by one.
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check if there are any other related codes present. These might provide further insight into the problem. | OBD-II Scanner |
Inspect the Cooling Fan | Visually inspect the fan for any signs of damage or obstruction that could affect its speed. Ensure the fan blades spin freely and are undamaged. | Flashlight, Safety Gloves |
Test the Fan for Low Speed Issues | Use a diagnostic tool to test the fan speed. Compare the actual fan speed to the manufacturer’s specifications to determine if it’s running too slowly. | Diagnostic Tool, Manufacturer’s Specifications |
Inspect the Fan Control Circuit | Check the wiring and connectors of the fan control circuit for any signs of damage, corrosion, or loose connections that could limit the fan’s speed. | Flashlight, Multimeter |
Check Voltage Supply | Measure the voltage supply to the fan to ensure it is receiving adequate power. A low voltage supply could cause the fan to run slower than intended. | Multimeter |
Clear the Code and Test Drive | After completing the necessary repairs, clear the P0494 code using the OBD-II scanner. Take the vehicle for a test drive to ensure the issue is resolved and the code does not return. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | After the test drive, re-scan the vehicle to ensure the P0494 code has not reappeared. If the code returns, further diagnosis may be required. | OBD-II Scanner |

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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)