Park/Neutral Switch Input Circuit High
What does P0852 mean?
The P0852 code means the vehicle's onboard diagnostic system has detected: Park/Neutral Switch Input Circuit High. This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Engine may start in any gear position
- PCM always reads transmission as in Park or Neutral
- Safety interlock does not function
Probable Causes (Ranked by Likelihood)
- Open circuit in park/neutral switch ground wire Very High
- Faulty switch stuck in open position High
- Short to voltage in signal wire Moderate
- Disconnected switch connector Moderate
Step-by-Step Diagnostic Procedure
-
Check for an open ground wire at the park/neutral switch
-
Verify switch connector is fully seated
-
Test for short to battery voltage on the signal wire
-
Monitor live data while moving the shifter through all positions
Frequently Asked Questions
Is it dangerous if the engine starts in gear?
Yes, this is a serious safety concern. If the PCM cannot tell which gear the transmission is in, the engine may start while in Drive or Reverse, causing the vehicle to move unexpectedly.
Is P0852 the opposite of P0851?
Yes. P0851 means the signal is stuck low (always reads in gear), while P0852 means it is stuck high (always reads as Park/Neutral).
Should I avoid driving until this is fixed?
Ideally, yes. The safety interlock exists to prevent injury. Have the vehicle towed if the engine can start in gear, or be extremely careful with foot placement on the brake.