Siemens VDO Piezo Injector (Part Number 03G130073S) .
This is a very specific and critical component for the 2.0 TDI PD (Pumpe Düse) engine. Here is the breakdown of the part, its applications, and critical information you need to know if you are replacing it.
1. Vehicle Compatibility
The part number 03G130073S is compatible with the Audi A3 2.0 TDI, but only with the specific engine code:
Engine Codes: BKD, BMM, BMN
Model Years: 2003–2008 (The 2009–2012 A3 2.0 TDI used a Common Rail engine, which takes a different injector).
It is also used in the VW Golf Mk5, Jetta, Passat, and Skoda Octavia of the same era with those engine codes.
2. Technical Specifications (Piezo vs. Solenoid)
This injector is part of the "Pumpe Düse" (Unit Injector) system but represents the second generation which uses Piezo technology.
Voltage: Operates at a high voltage (approx. 160V+) to actuate the crystal stack.
Difference: Unlike older solenoid injectors, these have no mechanical return springs for the needle. They are faster and allow for more precise multiple injections per cycle.
3. Critical: The "IQ4" Code (Laser Code)
If you are buying a new or refurbished injector, you must pay attention to the code on top of the old injector.
On top of the injector (under the black plastic cover/harness), there is a laser-etched code (e.g., "04P..." or a numerical value).
This code must be programmed into the Engine Control Unit (ECU) via VCDS (Vag-Com) or ODIS. If you do not code the new injector, the engine will run rough, smoke, vibrate, and have poor fuel economy.
4. Common Failure Symptoms
If you are replacing this part due to failure, common symptoms include:
Rough idle (especially when warm).
White/Grey smoke on acceleration.
Limp mode with DTC codes related to "Injector Circuit Malfunction" or "Implausible Signal."
Loud knocking from one cylinder.
5. Installation Tips
If you plan to replace this yourself:
Bolts: The two 10mm triple-square clamp bolts holding the injector down must be replaced with new ones. They are stretch bolts.
Cleaning: The injector bore in the cylinder head must be perfectly clean. Use a reamer tool if necessary.
Washer: Ensure you have a new copper sealing washer at the tip.
Lubrication: Lightly oil the O-rings and the new clamp bolts upon installation.
