Powertrain
generic / SAE
P0851
Park/Neutral Switch Input Circuit Low
Voltage on the park/neutral switch input is below the expected window. Wire shorted to ground or switch stuck closed.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number8 / 51
Possible causes
- Wire shorted to ground high
- Switch stuck closed medium
- Connector pins corroded - high contact resistance low
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 60–300 €
- Estimated time: 0.3–1.5 h
- Component: park neutral switch
- Component: wiring harness
- Component: ecm
- MIL / check engine light
Sources
References
sae:J2012