The EPC light on your vehicle might be turned on when you turn on the electronics. But as soon as you start the engine, the EPC light goes off. It comes up again when you shut off the engine and the electronics remain on.
So, why the EPC light goes off when engine starts?
- A faulty throttle body
- Brake light switch
- ABS sensor
- Brake pressure sensor
- And the steering angle sensor can cause the EPS light to go off when the engine starts.
I will explain the reasons and suggest some effective fixes to this problem. Let’s get into it.
Why the EPC Light Goes Off When the Engine Starts?
EPC stands for Electronic Power Control and it is a throttle management system. Brands like Volkswagen, Audi, and Porche use this system to sense if anything is wrong with the throttle body.
Though these vehicles also have the ECU, the EPC system monitors various functions of the throttle body. It collects data from different sensors and the EPC light comes on when any of the components are faulty.
Here is what can cause the EPC light to turn on and then go off when the engine starts.
1. Faulty Throttle Body
As you press the accelerator, the throttle body determines how much air should go into the engine. This is controlled by the EPC. Sometimes, you might experience rough acceleration or engine misfires while pressing the gas pedal. You can also experience a whining noise when revving the engine in neutral.
That happens because of a faulty throttle body. In such cases, the EPC light will come on when the electronics are on. And it will go off when the engine starts.
Solution
The valve on the throttle body might get jammed due to excessive soot. In such cases, you need to clean the throttle body.
Open the intake manifold to access the throttle body and clean the soot from the valve. But if the valve is damaged, you need to replace it. Depending on your car model, the throttle body can cost up to $500. And labor costs can be about $100-$150.
2. Faulty Brake Light Switch
The brake light switch determines if you have pressed the brake pedal. When the brake pedal is pressed, the brake lights turn on. But if the switch is faulty, the brake lights won’t come up after pressing the brake pedal.
In another case, the brake lights won’t turn off after releasing the brake pedal. This is when the EPC light comes on and goes off if the engine starts.
Solution
Different brake light switches are used in different vehicles. So you must check the owner’s manual first. The switch should be inside the brake assembly. Take a multimeter and check the voltage between the two connection points of the switch.
If there is no voltage, you need to replace the switch. And it will cost about $200-$350, including the labor charge.
3. Faulty ABS Sensor
It is a common cause of the EPC light going off when the engine starts. ABS sensors are used to measure the wheel speed and each wheel hub has one sensor.
If the sensor is faulty, the EPC light will come up. When you start the engine, the EPC light might go off. Sometimes, the check engine light will also come up.
Solution
You can use an OBD II scanner to read the error code on your vehicle. I suggest using the BlueDriver Bluetooth Pro OBD II Scanner. If the ABS sensors turn out to be faulty, you can replace them at about $500 per sensor including the labor cost. I suggest not to replace the sensors yourself unless you have extensive experience.
You can learn more about Engine Codes P0016 and P0017 here.
4. Bad Brake Pressure Sensor
This sensor measures the pressure exerted on the brake pedal. If the sensor doesn’t work properly, the EPC light will come up and then go off. As this sensor is paired with the ABS control module, replacing the faulty sensor is a big hassle.
Solution
The only solution is to change the whole ABS module. It might cost you $1,000-$1,500 to replace the module where the parts and labor cost are included. Get it replaced by an experienced mechanic.
5. Faulty Steering Angle Sensor
This sensor measures the steering wheel rotation angle to figure out the vehicle’s heading. But if the sensor is faulty, the system can’t work properly and the EPC light comes on. Then, it goes off when the engine starts.
Solution
Replacing the steering angle sensor is necessary to solve the problem. It might cost you about $150-$250 to change the sensor, including the labor cost. DIY replacement isn’t a good idea here.
6. Damaged Wiring
Sometimes, all sensors might work fine and the EPC light still comes on. It may happen due to any damage to the electrical wiring of the vehicle.
Solution
You must get the vehicle inspected by an experienced mechanic to find the faulty wiring. It can cost several hundred dollars, depending on the time.
People Also Ask
Check answers to some commonly asked questions about EPC lights.
Will the EPC light prevent a car from starting?
In most cases, the EPC light doesn’t prevent a car from starting. But if there is any problem with the engine sensors, the car might not start.
Can I drive with the EPC light on?
Yes, you can drive with the EPC light on. But I recommend getting the error checked and fixed as soon as the EPC light shows up. It will help you avoid more serious issues.
Can I fix the EPC light with OBD II scan tools?
For some error codes related to electronic problems in the car, you can clear the codes with an OBDII scanner. But if the problem is with sensors or other physical components, you need to replace that component.
End Notes
Though the EPC light doesn’t indicate any major issue, fixing the EPC light shouldn’t be ignored. Driving a vehicle with a faulty brake sensor, ABS sensor, or brake light sensor can invite risky situations. And you need to know the exact reason for the EPC light coming up and going off.
I mentioned the most common causes of why the EPC light goes off when engine starts and shows the solutions. Use them to get rid of the annoying EPC light and drive safely.
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