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Home >> Subaru >> 2019 >> BRZ Series.Gray >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (3 Of 3) >> EFI System (FA20) >> DTC P0851: Neutral Switch Circuit Low; DTC P0852: Neutral Switch Circuit High >> Circuit description >> Notes
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Circuit description: Notes

The engine control computer detects that the transmission is in the neutral state based on the signal from the neutral position switch (for Transmission M/T) or the neutral start switch ASSY (for Transmission A/T).

DTC DETECTION CONDITION

DTC No. DTC detection conditions Suspected parts
P0851 Transmission M/T
When shifting the gear position while driving the vehicle, the neutral position switch is left "Low". (Detected based on the change of relationship between the vehicle speed and the engine speed) (2 trips detection logic)
  • Open or short condition in the neutral switch signal circuit
  • Neutral start switch
  • ECM
Transmission A/T
When the range selector is neither in N nor P range, the neutral switch is in P or N range and the range information from the transmission control computer indicates a position other than P or N range.
  • Open or short condition in the neutral switch signal circuit
  • Neutral start switch
  • ECM
When the range selector is in N or P range, the neutral switch is in P or N range and the range information from the transmission control computer indicates a position other than P or N range.
  • TCM
P0852 Transmission M/T
When shifting the gear position while driving the vehicle, the neutral position switch is left "High". (Detected based on the change of relationship between the vehicle speed and the engine speed) (2 trips detection logic)
  • Open or short condition in the neutral switch signal circuit
  • Neutral start switch
  • ECM
Transmission A/T
When the range selector is in N or P range, the neutral switch is in a range other than P or N ranges and the range information from the transmission control computer indicates P or N range.
  • TCM
When the range selector is neither in N nor P range, the neutral switch is in a range other than P or N range and the range information from the transmission control computer indicates P or N range.
  • Open or short condition in the neutral switch signal circuit
  • Neutral start switch
  • ECM