Epc showing on the dashboard of audi a4 2007. Light comes...

Hello, my name is \*\*\*\*\* \*\*\*\*\* I will be helping you with your question today. I've been working on Audis for over 30 years now, so I should be able to help you through this. Please understand that some of my suggestions may require special diagnostic tools and equipment that many home mechanics may not have, but are often required. So, my first question is whether you're planning on performing your own repairs, or are you wanting to be armed with information before bringing it into your mechanic? **Also, the site automatically prompts for a phone call. It's very rare that I'm available by phone, so let's hold off on that for now. If needed after we exchange some information, I will do my best to take the time for the call.** Couple of other questions/points - can I get a VIN please? - have you already had the engine and EPC systems scanned for fault codes using VCDS or other Audi specific scan tool?

No I haven't

Ok, that is very important. The EPC is indicating a failure with your electronic throttle control. I'll post some detailed information about how it actually works, but a system scan using a proper scan tool will be necessary to diagnose the no-start

The local mechanic where I am doesn't have the toolThat's why I'm checking b4 having them come to check it

And I'm actually seeing this as a 2006 model year

My docs indicated a 2007 but that's pkOk

Not that it makes a large difference. Here is what I'm seeing directly from Audi: [https://i.imgur.com/XrEwk1Y.png](https://i.imgur.com/XrEwk1Y.png) First the details about EPC information 1. **EPC** stands for Electronic Power Control. This is the drive by wire throttle system used in Audi Lamborghini and VW gasoline models starting around the 2001 m.y. 2. How the system works: A. 2 position sensors located on the accelerator pedal (Throttle Position (TP) Sensor G79 and Sender 2 for Accelerator Pedal Position G185) transmit driver demand (intent) to the Engine Control Module (ECM). i. The G185 signal is always 1/2 of the G79 signal for plausibility testing. B. The ECM interprets the signals from the G79 and G185 sensors along with signals from other systems (engine, ABS, AC, transmission) to determine the output power sent to the Throttle Valve Control Module J338. C. The Throttle Valve Control Module J338 receives the power from the ECM and moves accordingly. There are 2 position sensors on the J338 module (Angle Sensor 1 for Throttle Drive G187 and Angle Sensor 2 for Throttle Drive G188) that provide feedback to the ECM on the current position of the throttle plate. i. The two sensors sweep in opposite directions for plausibility testing (i.e. one goes from 0.5 V up to 4.5 V while the other goes from 4.5 V down to 0.5 V). If the voltage of the two sensors is added together, it should equal the reference voltage into the sensors. 3. Major inputs to the calculation for the **EPC** system are: - Throttle Position (TP) Sensor G79 - Sender 2 for Accelerator Pedal Position G185 - Throttle Valve Control Module J338 - Angle Sensor 1 for Throttle Drive G187 - Angle Sensor 2 for Throttle Drive G188 - Brake Light Switch F - Mass Air Flow (MAF) Sensor G70 4. Any fault codes or situations that can affect how the throttle body is controlled or will respond can cause the **EPC** light to illuminate. 5. In a Key On Engine Off (KOEO) situation, the throttle plate should respond according to the accelerator pedal. (i.e. if the accelerator pedal is depressed 1/2 way, the throttle plate should open 1/2 way.) 6. If the engine is running, the ECM calculates the opening of the throttle plate based on multiple inputs (see step 2B).

So, this could mean a throttle body failure, throttle pedal failure, or other less common issues. However, once you get that system scan done and get a list of fault codes, I'm certain I can help further.

My left front brake band needs changing. Could that also contribute?Also is it possible it's the battery failing?I've asked the local mechanic to come with a spare battery

The brake pads? That wouldn't cause this. A battery failure could be a contributor though.

Ok. I will try with the new battery when it comes since I dont have the scanner nearby until I get a scanner

Ok, sounds good. Once the battery is replaced, don't try to immediately start the car. Turn the key to position 2, where the whole car is powered up. Leave it there for a minute, and then try to start. This \*might\* reset the throttle body

Ok. They should be here any minuteI will try and get back to u

Ok, I'll be offline shortly. If this doesn't work, then the Audi specific scan tool like VCDS will 100% be needed to diagnose it properly: [https://store.ross-tech.com/shop/vchv2\_ent/](https://store.ross-tech.com/shop/vchv2_ent/)

Sure. Thanks

very glad to help