CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Audi EPC

,

I have a 2007 Audi A4 4 door sedan with 62,000 miles. Its a great car EXCEPT periodically the car has trouble starting and then will buck or lurch a bit. The EPC light comes on and sometimes so does the check engine light. The bucking/lurching lasts for a minute or 2. Sometimes the EPC light turns off. I’ve taken the car to both the Audi dealership as well as to a local mechanic. Neither have been able to diagnose the problem or replicate it for that matter. Several days ago I had the same problem except when the bucking/lurching subsided, I could not accelerate beyond 30 mph for several minutes. The car “shifted” beyond 30 mph and is now running fine. EPC light is off but check engine light remains on. BTW - when this happened the first time, we thought it might be the battery. We replaced the battery but there seems to be no correlation between the battery and the symptoms.

Would love your thoughts!

Thanks

The EPC light indicates there’s a problem with the Electronic Power Control circuit.

Your vehicle doesn’t utilize a traditional throttle cable. But instead has a throttle pedal position sensor that sends an electrical signal to a motor on the throttle body that operates the throttle plate.

Tester

Hi Tester - Does something about the throttle pedal position sensor cause the periodic bucking and lurching along the EDC light coming on? If so, can you explain it? Thanks much

I don’t see a throttle position sensor listed for you vehicle which is normaly mounted on the throttle body. However, I can find throttle pedal position senors.

So one must conclude that the computer is taking the information from the throttle pedal positon sensor to determine how far to open the throttle and the shift points of the transmission.

Tester

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.