Code Definition

P1278 — Fuel metering solenoid short to positive

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Audi

About P1278

P1278 is a manufacturer-specific powertrain diagnostic trouble code recorded for Audi vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1278 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1278 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The fuel metering solenoid, also referred to as the quantity adjuster on Audi and Volkswagen diesel injection pumps, sets how much fuel the pump delivers on each stroke. The Engine Control Module supplies the solenoid with battery voltage and switches the ground side with a variable duty cycle, moving the metering element against a return spring, while a position sensor feeds the actual position back so the module can close the loop. Because the module watches the voltage on its own control output, it can recognise when that line is being held at battery voltage instead of following the comman...

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