Error code

OBD2 P0851

OBD2P0851
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Park/Neutral Switch Input Circuit Low.

Severity

moderateCan drive, but may experience issues starting the engine or using cruise control.

Summary

P0851 indicates that the Park/Neutral Position (PNP) switch input circuit has low voltage, which can affect engine starting and cruise control functions.

Symptoms

  • Engine may not start if in park or neutral
  • Cruise control is disabled

Common Causes

  • Corrosion or water damage to the PNP switch
  • Misalignment of the PNP switch
  • Improper installation of an aftermarket remote starter

Diagnosis

  1. Check continuity in different shift positions
  2. Verify input and output voltage at the PNP switch
  3. Inspect wiring harnesses for damage

Fixes

  • Replace faulty PNP switch

FAQ

Can I drive with this code?

Yes, but you may experience issues starting the engine or using cruise control.

What should I check first?

Start by checking continuity and voltage at the PNP switch.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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