P0495
Fan 1 Overspeed.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 4
- AreaAuxiliary emission controls
- 95
- FaultThe specific fault in that area
What it means
P0495 is the generic code for the engine cooling fan 1 running faster than the control unit commanded. The engine control unit compares the requested fan speed or duty with the actual speed, or with the fan's feedback signal, and sets the code when the fan overspeeds beyond the allowed tolerance for longer than a set time. How the fan is controlled and monitored varies by model and engine.
Symptoms
- Cooling fan running at high speed when the engine is cold or only warm
- Loud fan noise after start-up or with the engine at idle
- Engine warning light on
- Fan running on for a long time after switching off, on models where this is possible
- Poor cabin heat or slow warm-up if the engine is overcooled
- Possible fan failure or erratic behaviour with air conditioning on
Possible causes
- Fault in the fan control module or fan driver circuit causing the fan to run at full speed regardless of commandlikely
- Short or damaged wiring, corroded connector or poor earth on the fan control or feedback circuitlikely
- Faulty coolant temperature sensor giving a falsely high reading so the fan is commanded and held at high speedpossible
- Faulty fan motor or its integral electronics giving wrong speed feedbackpossible
- Air conditioning pressure sensor or request signal fault leading to unwanted high fan demandpossible
- Stuck or faulty fan relay on systems that use relays for fan speed stagespossible
- Fault or outdated software in the engine control unit affecting fan controlrare
How to diagnose
- Read all stored codes and freeze frame data, noting coolant temperature, engine load, vehicle speed and air conditioning status when the code set
- Check whether the fan runs at a cold start and whether it speeds up and slows down as expected with engine temperature and air conditioning demand
- Inspect the fan wiring, connectors and relays or control module for chafing, water ingress, corrosion and heat damage
- Compare live coolant temperature with the true engine temperature to check the sensor is reading correctly
- Check the fan commanded speed or duty against actual speed in live data, if the vehicle supports it
- Test the power, earth and control signals at the fan connector using the manufacturer's wiring diagram
- Check air conditioning pressure sensor readings and request signals if the fan runs with air conditioning on
- Swap or substitute-test relays only where the system uses them, and check for any technical bulletins or software updates for your model
How to fix
- Repair or replace damaged wiring, connectors or earths in the fan circuit
- Replace a faulty coolant temperature sensor or air conditioning pressure sensor
- Replace the fan assembly or fan control module if it is proven faulty
- Replace a stuck or faulty fan relay where fitted
- Update or reprogram the engine control unit software only if an outdated or faulty calibration is confirmed as the cause for that model
Can I keep driving?
Low severity
The car can normally be driven as the fan running too fast does not usually cause engine damage, though noise and extra battery load may be annoying. Book it in soon, and stop if the temperature gauge rises or the fan behaves erratically.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.