P0850 moderate

Park/Neutral Switch Input Circuit

The P0850 code means the vehicle's onboard diagnostic system has detected: Park/Neutral Switch Input Circuit. This is a moderate severity code.

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Keep driving?
Short distances only
DIY difficulty
moderate
Estimated cost
$75 - $400 (parts and labor)
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ANCEL AD310 OBD-II Scanner

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Common Symptoms

  • Check Engine Light illuminated
  • Engine will not start in Park or Neutral
  • Engine starts in gear positions
  • Backup lights or gear indicator malfunction

Probable Causes (Ranked by Likelihood)

  • Faulty park/neutral position switch Very High
  • Misadjusted shift linkage High
  • Wiring fault in park/neutral switch circuit Moderate
  • PCM input circuit failure Low

Step-by-Step Diagnostic Procedure

  1. Check if the engine starts in Park and Neutral only

  2. Test the park/neutral switch with a multimeter

  3. Verify shift linkage adjustment at the transmission

  4. Inspect wiring between the switch and PCM for damage

Frequently Asked Questions

What does the park/neutral switch do?

The park/neutral switch (also called the neutral safety switch) tells the PCM which gear the transmission is in. It prevents the engine from starting unless the transmission is in Park or Neutral.

Is a park/neutral switch the same as a transmission range sensor?

They serve similar functions. Older vehicles use a simple on/off neutral safety switch, while modern vehicles use a transmission range sensor that provides the exact gear position to the PCM.

Can I start my car by shifting to Neutral if Park does not work?

Sometimes this works as a temporary workaround, but it indicates the switch is failing and should be repaired soon to avoid being stranded.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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