Powertrain, generic · Transmission

P0852 Park/Neutral Switch Input Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

  • Engine does not crank in P/N (automatic)
  • High or rough idle
  • Cruise control blocked

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

park neutral switchtransmission range sensorswitch wiringengine control module

Related codes

P0850P0851P0705P0708P0817

References: saabwisonline.com, saabwisonline.com, saabwisonline.com, gsi.ext.gm.com.