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P0494 OBD-II Trouble Code: Fan Speed Low

Check Engine Light

Diagnostic Trouble Code (DTC): P0494

P0494 code definition

If the PCM has detected a voltage reading that is too low from the electric cooling fan control circuit, the P0494 code will be stored.

What the P0494 code means

The P0494 code relates to the engine cooling and air conditioner systems. In order ensure that the engine temperature remains at the right level, and that the air conditioner is operating correctly, the PCM gathers data from the circuitry in the cooling fan control system. If this data is more than 10% lower than the voltage specified by the manufacturer for the current driving conditions, then the PCM will store the P0494 code.

What causes the P0494 code?

Most of the time, a bad cooling fan motor, or a faulty cooling fan relay, are to blame for this code. However, there are some less-common causes that should be considered, such as:

What are the symptoms of the P0494 code?

In most cases, the illuminated Check Engine Light will be the only observable symptom. Some vehicles may overheat, and the air conditioner may not work as efficiently.

How does a mechanic diagnose the P0494 code?

After verifying the code with an OBD-II scanner, the mechanic should begin with a visual inspection of all wiring and other electrical components, as well as vacuum lines and hoses. Any simple electrical issues, such as loose or shorted elements, should be repaired.

After this, or any, repair, it is important to clear the code and retest the system. If the code returns, then the mechanic must continue by checking the voltage of the primary cooling fan motor. The next step is to check the voltage readings of the engine cooling fan relay. If either of these parts are not meeting the manufacturer’s specifications, they must be replaced.

The mechanic should continue in this manner, diagnosing and retesting the system after each possible diagnosis, until the cause is found.

Common mistakes when diagnosing the P0494 code

The most common mistake when diagnosing and repairing this code is to replace a cooling fan motor without performing a thorough diagnostic procedure of the entire system. For example, cooling fan relays are frequently recalled, and may therefore be the true issue. It is important to diagnose all possible problems before replacing any major parts.

How serious is the P0494 code?

If the P0494 code is stored in the PCM, it represents a serious issue that should be repaired immediately. Although no major symptoms are usually observed, the inability to measure and control the cooling system will eventually lead to larger and more expensive repairs. It is important to have this issue fixed as soon as the code is detected.

What repairs can fix the P0494 code?

There are a few ways that a technician can address a P0494 code detection. They include:

Need help with a P0494 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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