So I sat in my 2001 Audi A4 1.8t the other night to leave work and upon starting, the engine was shaking and hesitating. I drove it the 1 mile home from work with decreased power and responsiveness and a CEL came up. I scanned it with vagcom and got a few codes:

18014-Rough Road/Engine Torque Signal from ABS: Electrical Malfunction
P1606-35-00--
16684-Random/Multiple Cylinder Misfire Detected
P0300-35-00
16688-Cylinder 4 Misfire Detected
P0304-35-00

When I got home, I let the engine cool and did a google search. I found that it was most likely a faulty coil pack which I had initially thought might be the case. I then started the car and pull the cyl #1 coil pack and the engine stuttered, so I knew that coil was good. I then replaced #1 and pulled #2. At this point, the car sputtered and the engine stopped. I tried restarting the car, but it only cranks and doesn't fire. I unhooked the battery to let it charge and thinking I flooded the engine, I let it sit for a few hours and charge. I scanned for codes again and got the same codes as before plus these:

16685-Cylinder 1 misfire detected
P0301-35-00
16705-Engine Speed Sensor(G28): Implausible Signal
P0321-35-00
18010-Power Supply B+Terminal 30: Voltage too Low
P1602-35-00
16706-Engine Speed Sensor (G28): No Signal
P0322-35-00

At this point, I found that there was probably either a loose connection or a bad G28 sensor, so I ordered one from Autozone with a 2 year warranty. Since I had been cranking for quite a while at this point, I decided to unhook the battery and charge it overnight.

The next morning, I replaced this sensor, put the key in and tried starting the car, but no dice. The engine still will not start. I again scanned for codes and have:

18010-Power Supply Terminal 30: Voltage too Low
P1602-35-00

I believe this last code is because I had the battery unhooked. I have pulled the #1 spark plug to verify I am getting fuel. Upon pulling the plug, it is wet and has the smell of gasoline, so I don't believe this problem is due to fuel. I believe it is an electrical problem some where, but I don't know where. I believe the power supply terminal 30 code is from unplugging the battery, but maybe not. The battery is only a few months old! If anyone has any ideas, please help!

 

Sounds like a problem I am having. I got a P0301 code. Engine was running rough. Changed my plugs and coil packs and now it wont start at all. Changed everthing back to original and still wont start. Basically, my improvements went backwards.

 

Dont disconnect the battery this time, clear the codes, then try to start the car again (and before you try and start it again, leave the key turned to the on but not running position for at least 4 minutes, this has to do with you disconnecting the battery and calibrating the throttle body) and see what codes come back. When its running, dont just pull a coil pack, you should swap them and see if the misfire code moves (if it does then you know its a bad coil pack). So if 4 is misfiring, move the coilpack from 4 to say, 2 and move 2's coilpack to 4. Clear the codes and see if you now have a misfire on 4. If the code doesnt move with the coilpack, then try moving the spark plugs.

That supply voltage is because the battery was disconnected.

Since you didnt have the code for the engine speed sensor before you disconnected the battery it makes me wonder whether it is actually bad, thats why I would clear the codes, try to start it, and scan again. If the code comes back I would def replace it.

 

try changing out the speed sensor/knock sensor... the connector is under the coolant resivouir, then you can follow the wire down the driver side of the block above the oil pan, it is 2 10mm screws holding it in

you can get the part online, dealer or maybe autozone


i have very similar issues to where i thought the car was going to blow up

 

Did you fix it ? How same exact problem