Technical Description of OBD-II Trouble Code
High Fan Speed
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles (Chevrolet, Buick, Peugeot, Toyota, Citroen, Dodge, BMW Honda, Acura, Ford, Dodge, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The cooling fan mentioned in these codes is typically mounted on the radiator. Its purpose is to cool down the coolant in the radiator and help regulate the engine temperature.
The engine control module (ECM) or powertrain control module (PCM) monitors and controls various sensors to regulate the engine temperature. The ECM activates the fan when the engine temperature rises (e.g., idling in traffic) and deactivates it when there is sufficient airflow to keep the temperature down (e.g., cruising on the highway).
The ECM has detected a high-speed condition while monitoring the cooling fan. If the cooling fan is spinning beyond or below the manufacturer’s set parameters, the engine light or malfunction indicator lamp (MIL) will be illuminated by the ECM.
Related engine cooling fan diagnostic codes:
Symptoms
Symptoms of a P0495 engine code may include:
Potential Causes
Typically, the causes for this code to set are:
Diagnostic and Repair Procedures
When working with electrical systems, it is recommended to have the following basic tools:
Safety Tips
Basic Step #1
Perform a visual inspection. Start by opening the hood and locating the radiator/fan assembly. In most cases, it will be mounted towards the front of the vehicle, directly in front of the engine. Note that there are various styles and setups for cooling fans, some mounted directly on the radiator and others belt-driven by the engine. Identify the style of your particular cooling fan. Once located, inspect the fan(s) and blades for any damage. It is advisable to lightly shake one of the fan blades to check for any play in the bearings. Depending on the style and amount of play, you may need to replace the fan assembly. Also, inspect the shroud and anything that may obstruct the fan’s performance. Pay close attention to the wiring harness for the cooling fan, as even one lightly frayed wire can trigger certain codes. If everything appears to be in order, proceed to the next step.
TIP: Sometimes aftermarket shrouds do not fit perfectly, causing the fan to rub against parts of the shroud and resulting in a low-speed condition. With the engine off and cold, spin the fan by hand. It should spin freely in the shroud (you may need to remove the belt for the belt-driven version).
Basic Step #2
Check the connector. First, ensure that the battery is disconnected before performing any repairs or tests on the electrical system. Follow the harness coming out of the cooling fan until you find its connector. Once located, inspect it for overheating/melting or corrosion. Disconnect the connector and inspect the pins inside. Any corroded or bent pins must be repaired or replaced. Typically, any damage to the connector necessitates its replacement. If everything looks good, proceed to the next step.
TIP: Ensure that you have a healthy electrical system. Always be aware that if you have a weak battery or a problem with your charging system, the ECM may falsely illuminate the engine light, among numerous other possibilities.
Basic Tip #3
Check the relay. Depending on your system, you may have a cooling fan relay that assists in controlling your fan. Refer to the manufacturer for its location. If the relay appears melted or burnt, this may indicate a problem within the relay and it should be replaced.
TIP: It is advisable to purchase these types of relays from your manufacturer’s dealership, as I have encountered some defective aftermarket relays that have caused significant damage.
Basic Step #4
Check your ECM or PCM. Locate your ECM. Its location heavily depends on the make and model of the vehicle, but you may find the ECM under a seat, under the hood, in the trunk, mounted to the firewall, under the dash, in a fender, or mounted to the floor somewhere. Once located, inspect it for water damage or corrosion, as this may indicate a problem. Beyond this point, professional assistance would be required.
