Error Code P0852 is referred to as Park/Neutral Switch Input Circuit High. Error Code P0852 is a generic trouble code, meaning it applies to all vehicles with the OBD-II system, especially those made from 1996 up to the present. It also applies to vehicles with both automatic transmission and 4WD capability. Specifications on the definition, troubleshooting, and repairs vary between make, model, and powertrain configuration.

If the PCM stores this code, this means the input circuit, which measures the function of the park/neutral switch, is showing a reading that is too high compared to the specifications set by the manufacturer for the present driving conditions.

The PCM (powertrain control module) uses data from various sensors that make up the park/neutral switch input circuit to calculate essential operations, such as engine RPM, engine timing, fuel delivery, etc. If the data the PCM receives shows that the transmission shifter range is higher than the specifications/parameters set by the manufacturer, then it will store this error code.

Common Symptoms

As with other error codes, the Check Engine Light is activated with this code. Other common symptoms include:

  • Harsh shifting or failure to shift
  • Unable to engage 4WD
  • Increased fuel consumption

Possible Causes

A misadjusted transfer case range sensor usually causes this error code. This could have resulted from improper installation from the previous repair. Other possible causes include:

  • Defective range sensor
  • Improperly installed sensor retaining bolts
  • Corroded sensor circuits
  • Open, shorted, corroded, or damaged electrical components such as connectors and wirings

How to Check

First, use the OBD-II scanner to verify the error code. After this, you can proceed with the visual inspection of the electrical components, i.e., connectors and wirings. Repair or replace as necessary, then clear the code, reset the system, and see if it comes back.

If the code comes back, check the battery voltage and ground signals at the park/neutral switch.

Make sure you compare the readings with the specifications set by the manufacturer. If the readings are within the acceptable range, then the sensor is in good shape. However, if the readings are outside the acceptable range, then try other repairs. Ensure you clear the codes and reset the system after each potential repair process to ensure the correct repairs are being done.

How to Fix

  • Proper readjustment of transfer case range sensor
  • Replacement of faulty range sensor
  • Replacement of corroded sensor connector
  • Repair or replacement of any open, shorted, corroded, or damaged electrical components such as connectors and wirings
  • Proper reinstalling of sensor retaining bolts

The most common mistake in diagnosis this code is assuming the transfer case range sensor is faulty when it is misadjusted.

Since this code related to the drivability of the vehicle, the fault is considered urgent. Allowing the problem to sit can cause severe damage and result in unsafe driving conditions, which can lead to more expensive repairs.

If this code is detected, it is best to take your vehicle to a qualified technician. They have the expertise and advanced tools for a thorough diagnosis and proper repair.