What causes the EPC light to come on?

Tiny
JYOUNG123
  • MEMBER
  • 2013 VOLKSWAGEN JETTA
  • 2.5L
  • 5 CYL
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
After they diagnosed the car the EPC light was off the came on after driving on the highway. It randomly comes on driving around town.
Thursday, June 3rd, 2021 AT 6:01 PM

4 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
More then likely we have an issue with the throttle position sensor or related component.

The EPC stands for Electronic Power Control and it basically is talking about the throttle, traction control, and cruise control.

However, we need to start with checking for codes to find out what is there so that we can get a better idea which system the issue is related to.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

What was the vehicle at the shop for? What did they do and was this light coming on prior to them working on it? Also, was this something that they tried to repair?

let's start with this info and go from there. Thanks
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Thursday, June 3rd, 2021 AT 6:50 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,544 POSTS
Hi,

The EPC (electronic power control) light can indicate a few different things. What code was found and was there only one?

As far as the EPC, it could be related to the throttle pedal sensor, throttle body, the traction control system, the cruise control system, and so on.

Did the ABS or brake light ever come on? Also, do you know the codes that were found when it was checked and turned off?

Let me know.

Joe

.
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Thursday, June 3rd, 2021 AT 6:53 PM
Tiny
JYOUNG123
  • MEMBER
  • 5 POSTS
Code P3078.
No ABS or brake light.
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Friday, June 4th, 2021 AT 2:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,544 POSTS
Hi,

The code indicates, "Throttle Control Airflow At Idle Too Low."

Okay, what I suggest is this. First, we need to confirm there are no intake manifold leaks or engine vacuum leaks. Here is a link that will explain how it's done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If nothing is found, I suggest servicing the throttle body. If it is excessively dirty, that can cause this code as well. Here is a link that explains how it's done:

https://www.2carpros.com/articles/throttle-actuator-service

Also, make sure the air filter is clean, the air inlet tube between the throttle body and air filter box is clear, and do a general inspection for broken, cracked, or disconnected engine vacuum hoses. That part is explained in the first link I attached.

Let me know what you find or if you have other questions.

Take care,

Joe
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Friday, June 4th, 2021 AT 8:04 PM

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