SIEMENS PD PIEZO INJECTORS
SIEMENS PD PIEZO INJECTOR
These injectors are used on all 2.0 PD TDi Passat engines. (Not 1.9 PD TDi engines)
The electrical connector on a Piezo injector faces upwards and not sideways like a Solenoid injector.
Other than this, Piezo and Solenoid injectors look similar, with the injector nozzle looking like a fat nail and the pump looking like a valve spring. These injectors are always held in by two bolts.
Piezo injector failure seems mostly due to an internal electrical fault in the Piezo valve. The internal piezo wiring seems to burn out and short to the casing. The Piezo valve voltage signals are 100 -200V. Rather than risk damage to the ECU when one “shorts”, the ECU switches them all off.
The engine will cut out instantly and will not restart.
A VCDS or similar scan may give a fault code of:
17448 P1040 - Supply fuel injector(s) A, electrical malfunction in circuit
18578 P2146 - Supply Voltage for Fuel Injector Group A, Open Circuit
18579 P2147 - Supply Voltage for Fuel Injector Group A, Short to Ground
18580 P2148 - Supply Voltage for Fuel Injector Group A, Short to B+
17447 P1039 - Supply fuel injector(s) A, shorted
How to find the dud injector.
Pull the connector off an injector and start the engine. If it starts and runs on three cylinders, you have found the dud injector. Pull off, test and replace connectors until you find the dud injector.
Testing an injector.
You can’t test an injector for function but you can check the Piezo valve wiring. As this is the bit that normally fails, it is worth checking.
The piezo socket on the injector has TWO pins.
Neither should be connected to the casing (Earth or “-“).
Set your multimeter to continuity or Ohms.
Place one probe on one connector pin and the other probe on the injector body.
The meter should read “1” and not buzz.
Repeat for the other connector pin.
If the Piezo valve has failed the meter will buzz or give a reading. A failed injector will give a reading of 400 – 500 Ohms or less.
If you are new to multimeters, an Ohm reading of “1” is not less than 400 – 500.
“1” means infinity or super super high resistance, in other words, no connection.
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