Engine Misfire: Troubleshooting & Error Codes

Translated on 13-08-2026, 5:12.

I've been browsing Diesel Schrauber for a while now, and I finally decided to take the plunge and register. By the way, it's a really great forum

.

Now, regarding my problem:

I drive an Audi A3 8L (engine code: ATD) that starts to stutter at specific RPM ranges, namely at 2700 RPM and 2900 RPM. This is particularly noticeable on the highway in 5th gear, but it happens rarely otherwise.

I visited a friend who is a chip tuner. He came along for a test drive with my car and used VAG-COM to diagnose it. He thought the VTG (Variable Turbine Geometry) was sticking. At that time, the car didn't go into limp mode, so no error codes were stored. My friend suggested that a few minutes of full throttle driving on the highway would fix the problem. It worked for a day, but then the issue reappeared.

After it went into emergency mode twice after that, I took it to another mechanic friend. He had a SUN diagnostic tool that showed the following error:

18074 - Valve for pump/nozzle, cylinder 1 (N240).
Electrical fault in circuit P1666.

Based on my research, the wiring harness would normally be a suspect, but what's strange is that it always happens at the same RPM range. It runs smoothly at idle, and accelerates normally up to that specific RPM range.

My question is: could it still be the wiring harness?

Sure, no problem.

emil

Translated on 13-08-2026, 5:14.

Quote:

my question: could it still be the wiring harness?

Okay. I would start by replacing the wiring harness before you deal with the potentially expensive power distribution modules (PDs). However, a faulty PD is still a possibility.

Translated on 13-08-2026, 5:15.

Hi,

According to the error description, I would start by replacing the wiring harness for the PD injectors. I had a similar problem with a Ford Galaxy II with an AUY PD engine. Everything was fine up to about 3000 RPM, but then the vehicle started to jerk and even went into limp mode. After restarting, it worked again for a while until the next failure. It's not that expensive initially, and maybe it will run smoothly again after that. Best regards.