Code Definition

P1903 — Engine coolant hydraulic blower motor solenoid shorted to positive

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

About P1903

P1903 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 P1903 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a signal or supply voltage lower than the expected operating range.

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.

P1903 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

DTC P1903 sets when the engine control module (ECM) detects a short to positive in the engine coolant hydraulic blower motor solenoid circuit. On the Audi models that use it, the main cooling fan is driven hydraulically rather than by an electric motor, using pressure supplied by a pump, and this solenoid valve controls how much flow reaches the fan and therefore its speed. When the solenoid control circuit is shorted to positive, the ECM loses proper control of fan speed, which can cause the fan to run continuously, run erratically, or draw excessive current. Depending on the fault the driver...

Join TaT to view the complete code information and diagnostic details.

Quick Facts