P0203 and P0303 Please help!!!!!

[zlaja80]

Please help!!!!!
I have a 2003 A4 1.8T FWD with 196,000miles. This issue started yesterday out of the blue. It was a slightly chilly morning with humidity when I turned the car on. As soon as I started it, it started rough idling – erratic idling. Popped the hood and I could see the engine vibrating. The CEL started blinking, hooked it up to the OBD II scanner and came up with two codes. I read numerous posts about this, but I am not sure what to do.

P0203 – Cylinder 3 injector circuit malfunction
P0303 - Misfire cylinder 3

About 5 months ago I bought some coils from Advance Auto – I know I should not have bought those as these cars do not like anything except OEM or Audi. At that time I was on a tight budget. They lasted about 5-6months and I did end up replacing one of those Advance auto coil packs with my original Audi that was still good few months ago as it did a similar thing to what it is doing now, less the bad injector code.

I had another Audi coil pack in my trunk so I swapped the Advance auto part yesterday. Once I did that everything calmed down. I cleared the codes however today at lunch I was adding some oil to the engine, and afterwards started it. As soon as it started it started doing the same thing.

Turned it off, unhooked the coil harness again, pulled that cylinder 3 coil pack cleaned it a bit from the White residue (not sure what this is) that was on the inside and put it back in. That seemed to solve the issue. As the idling got smooth like nothing happened.

Am I looking at the bad Coil packs and or could it be something else? Please Help!!!!!!!!!!!!!!!!!!!! Thank you very much for your help in advance!!!!!

[old guy]

The problem is probably coming from your number 3 fuel injector. The faulty injector circuit is causing the misfire thus the p0303

[zlaja80]

The problem is probably coming from your number 3 fuel injector. The faulty injector circuit is causing the misfire thus the p0303

Thank you sir, Am I safe to replace just that one injector? Would cleaning the injector work in this case, or it is something electronic inside? This question may sound dumb, however here it is Cylinder 3 is the third cylinder from front of the vehicle, correct! Thank you very much for your help!

[old guy]

Cylinder #3 is the third one back from the front of the engine. The DTC P0203 indicates an electrical rather than a mechanical failure with the #3 fuel injector. The first thing I would do is to closely examine the harness connector for any frayed or split wires. It may be as simple as unplugging the harness connector, cleaning it up and reconnecting it.

[zlaja80]

Thanks again!

[zlaja80]

Hi there, you were helping me with few codes P0203 and 0303.. I pulled the injectors and changed the o- rings, then I swapped injector 3 with 1. This morning, rough idle and missfire on cylinder 1, got P0301. Could it be a bad injector? No issues with cyl 3. Thanks a bunch!!

[old guy]

Yes it sounds like a bad injector.

[zlaja80]

Thanks again sir! I greatly appreciate the help!

[y0itzflip]

i wish all issues on this car were so easy to troubleshoot lol. good stuff.

[zlaja80]

P0201 and P0301 popping up. I will be changing that fuel injector Tuesday. I was hoping that someone in Richmond VA would have these in stock, of course except the Audi dealership.

[old guy]

PM me your ship to address and I will send you an OEM injector. It has 50k miles on it so it should still be good.