Code Definition

P1086 — Turbo Generator Valve Position Sensor 1 Circuit Low

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

About P1086

P1086 is a manufacturer-specific powertrain diagnostic trouble code recorded for Subaru vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1086 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

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.

P1086 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

On these Subaru engines the Engine Control Module (ECM) monitors the voltage from Turbo Generator Valve Position Sensor 1, which reports the vane or valve angle of the variable geometry turbocharger actuator. The signal normally varies with the actuator position within a defined voltage range. DTC P1086 sets when the ECM measures the sensor voltage below the permissible lower threshold for a defined time during turbo control, indicating an abnormally low or absent position signal. This usually means a short to ground on the signal circuit, a loss of the sensor reference, or a failed sensor. Sy...

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