View Full Version : First problem, EPC light

02-24-2015, 10:03 AM
Hi guys so my A4 is giving me my first test, the EPC light. Luckily it was accompanied by the CEL the third time the EPC light illuminated. Each time the EPC light goes on, there is a significant jolt from the engine as im driving, almost feel like I slam on the brakes for a hot second. Thats when the light illuminates adn the car become a complete turd. Still drivable but acceleration is noticably sluggish, like sunday driver sluggish and when I try to restart the car in an attempt to clear everything, the starting process takes a lot longer before everything fires right up, and then when it does fire up, it slowly comes up to idle. Then the next day everything will be fine and with no EPC light, car runs like new.

So I started doing a lot of reading and this seems like a common problem. Some say throttle body, others say vac leak, and Im also seeing stuff about the Eng speed sensor. Went to auto zone to get my codes read, the CEL remains on BTW but the EPC comes and goes, usually goes after its been sitting for hours before work. The computer spat out P0322, P0321, P0010, and P0012.

So far ive taken the throttle body out and cleaned it. Even took the plastic cover off to reveal the gears and brushes and all looked well. Cleaned in there too and bent the brushes more toward the slip board to ensure good contact. Plugged it back in and made sure it worked before bolting it back up. Found a loose vac line under the intake that connects to something beside the oil dip stick tube. Took it off to test out while the car was running and I could definitely hear the hiss of vacuum leak, but this did not trigger the EPC light. I even drove it around with the hose off, bringing it as high as 4K RPM, but no light, ran just fine. So I started looking around for more obviousness when I found a connector under the coolant expansion tank hanging down, not connected to anything.

Doubt its the cause since my problem comes and goes and the plug obviously doesnt unplug and replug itself. If so, then what kind of technology is Audi putting in these cars? [o_o]

Here is the plug. Just by the pic, anyone know what it is, what it does, where it connects? I cant seem to find its mate anywhere. And the wire goes into the main wire harness just under the expansion tank.

http://i1228.photobucket.com/albums/ee454/supersixone/0224151152a_zpshzlpvset.jpg (http://s1228.photobucket.com/user/supersixone/media/0224151152a_zpshzlpvset.jpg.html)

http://i1228.photobucket.com/albums/ee454/supersixone/0224151152b_zpsrplhmhq6.jpg (http://s1228.photobucket.com/user/supersixone/media/0224151152b_zpsrplhmhq6.jpg.html)

http://i1228.photobucket.com/albums/ee454/supersixone/0224151153_zpsy2jik5ix.jpg (http://s1228.photobucket.com/user/supersixone/media/0224151153_zpsy2jik5ix.jpg.html)

Any help is appreciated.

02-24-2015, 10:46 AM
That's the coolant level sensor plug, it connects to the bottom of the coolant tank.

Flashing EPC and engine running/starting problems are symptomatic of a faulty crank position sensor. They're cheap and relatively easy to replace, I'd start there.

For future reference, if you're going to post codes you should take the time to look them up and post their description for us. Saves us the hassle of copy and pasting each one to look them up for ourselves.

02-24-2015, 11:22 AM
So I had to make a road trip to visit some family, figured my problem was small enough to make the trip. The car ran fine the whole way up, but just yesterday I embarrassingly stalled the car on a hill at a stoplight in some horrendous traffic. And to add to the shame and embarrassment, the car wouldn't restart. It would turn over, crank, then die instantly. What's even worse is that I'm still rolling around with a dealer tag. Talk about embarrassing.

So I threw on my hazards, tried to restart, while gassing and by the 4th or 5th try she took, then died right in front of my parents house. Then I had an emergency with my bank account so I went back out in it and died out on the freeway. I pulled off to the side of the road and tried a restart and it was in full limp mode. She wouldn't rev over 2k. So I sat there for about 15 mins and restarted again and I had full power.

So this pushed me to go ahead and get the crank sensor. All the vw dealers are closed today but to my surprise an autozone near me had the duralast part. I have to do the same roadtrip back home today so I took it and swapped it out. Just took the car for a test drive and she ran fine, but only time will tell. Read the codes again and 0012 and 0010 is camshaft sensor open circuit and overretarded timing. I'll go after that next it the problem continues.

Taking a look at the old one, it looks like some plastic was hanging in front of the magnet. Other than that, it looked fine. My screw driver magnetized to it just fine. I still don't see how a part like that just fails. It's still doing magnet things. No moving parts. No sensitive equipment. Just some plastic and ferrous metal.