The park/neutral input tells the engine control module whether the automatic is in P or N, or a manual gearbox in neutral. It releases the starter, prepares idle control for the load of an engaged gear and enables cruise control and other monitors. All documented makers check it for plausibility against driving state or a second source such as the gearbox module. On GM's 6T70 and Subaru the switch pulls the line to ground in P/N. P0852 means the input wrongly reports a gear although P/N is selected: open wire, short to voltage or a switch that no longer closes. Subaru's manual sets it when neutral is never seen while the car changes three times between idle and 64 km/h, MIL after two trips. GM's LML Duramax sets it when the gearbox module reports P/N but the input does not, type B; the 6T70 after 0.2 s, type C.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Engine does not crank in P/N (automatic)
- High or rough idle
- Cruise control blocked
Most likely causes
- Signal or ground wire or connector open
- P/N or neutral switch does not close
- Selector cable or inhibitor misadjusted
- Signal wire shorted to voltage
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P0852 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 8: Transmission
- 52: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0852?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P0852?
The most common causes are: signal or ground wire or connector open; p/N or neutral switch does not close; selector cable or inhibitor misadjusted.
Related codes
- P0850Park/Neutral Switch Input Circuit
- P0851Park/Neutral Switch Input Circuit Low
- P0705Transmission Range Sensor A Circuit (PRNDL Input)
- P0708Transmission Range Sensor A Circuit High
- P0817Starter Disable Circuit/Open
Sources
- saabwisonline.com: dtc p0852 neutral switch input circuit high mt mod
- saabwisonline.com: dtc p0852 neutral switch input circuit high mt mod
- saabwisonline.com: dtc p0850 p0852
- gsi.ext.gm.com: 14OBDG10 Engine Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.