P0850 OBD-II Trouble Code: Park / Neutral Switch Input Circuit

Our certified mechanics come to you · Get a fair and transparent estimate upfront


Cost of diagnosing the P0850 code

P0850 is a diagnostic trouble code (DTC) for "Park / Neutral Switch Input Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate* Credit towards follow-up repair Earliest Availability
Ford $154.99 $50.0
Toyota $154.99 $50.0
BMW $164.99 $50.0

*Estimates may vary by market

SCHEDULE P0850 DIAGNOSTIC Get a fair and transparent estimate upfront

P0850 code definition

If the PCM has stored the P0850 code, it means that the input circuit which measures the function of the park/neutral switch has given an abnormal voltage reading.

What the P0850 code means

If the vehicle is put into park or neutral, voltage readings are sent to the PCM from a variety of sensors and components. This data helps the PCM ensure that park or neutral was achieved, and that the vehicle is operating correctly. If the voltage reading from the input circuit on the park/neutral switch does not match the manufacturer’s specifications, the PCM will store the P0850 code. This code is only applicable in vehicles with both an automatic transmission, and four-wheel-drive capability.

What causes the P0850 code?

In the majority of instances, the P0850 code is caused by a misadjusted transfer case range sensor. This could have been improperly installed during a previous repair.

Other causes may include:

  • Faulty park/neutral switch
  • Open or shorted park/neutral switch harness
  • Poor electrical connection in the park/neutral switch circuit
  • Defective range sensor
  • Damaged wiring or other electrical components
  • Improperly installed sensor retaining bolts
  • Excessively corroded sensor connector

What are the symptoms of the P0850 code?

In addition to the illumination of the Check Engine lamp, vehicle owners may observe symptoms such as the inability to engage the four-wheel-drive, harsh shifting or complete failure to shift, and a decrease in fuel efficiency.

How does a mechanic diagnose the P0850 code?

The first step is to verify the code with an OBD-II scanner. Once this step has been completed, the mechanic should begin with a visual inspection of all electrical components, including wiring and connectors. Repair or replace any parts as necessary, and then clear the code from the PCM and retest the system. If the code reappears, the next step is to check the battery voltage and ground signals at the park/neutral switch.

Throughout the diagnostic process, the mechanic should compare readings to the manufacturer’s specifications. If the readings are within the acceptable range, then suspect the sensor itself is bad; if the readings are not within the acceptable range, then other repairs will have to be attempted. Always remember to clear the code and retest the system after each potential repair, to ensure that the correct repair is pinpointed and time is not wasted on further repairs.

Common mistakes when diagnosing the P0850 code

The most common misdiagnosis is to blame a faulty transfer case range sensor, when in fact the part was not faulty, but simply misadjusted.

How serious is the P0850 code?

Because this code directly relates to the vehicle’s drivability, it is considered an important matter that should be addressed right away. Allowing the P0850 code to remain unrepaired could create unsafe driving conditions, and cause larger and more expensive repairs to be necessary. When the P0850 code is detected, it is best to have an auto service technician address the issue right away.

What repairs can fix the P0850 code?

There are many ways that a technician can address a P0850 code detection. They include:

  • Adjust transfer case range sensor
  • Replace faulty park/neutral switch
  • Repair open or shorted park/neutral switch harness
  • Repair poor electrical connection in the park/neutral switch circuit
  • Replace defective range sensor
  • Replace damaged wiring or other electrical components
  • Properly install sensor retaining bolts
  • Replace excessively corroded sensor connector

Need help with a P0850 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
trouble codes
P0850

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0850 code.

SCHEDULE P0850 DIAGNOSTIC
Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(8600)

Rating Summary
8017
273
65
46
199
8017
273
65
46
199
 at YourMechanic

Brandon

9 years of experience
133 reviews
Brandon
9 years of experience
Ford Escort L4-2.0L - Check Engine Light is on - Nashville, Tennessee
Brandon showed up ahead of schedule, was very personable and diagnosed my problems. He also scheduled my next appointments which will be with him.
 at YourMechanic

William

23 years of experience
33 reviews
William
23 years of experience
Lexus IS250 V6-2.5L - Check Engine Light is on - Mableton, Georgia
Arrived early which was great. William was courteous, and attentive to the issue. Even though it took several attempts I'm so happy he was determined to fix it and he did!
 at YourMechanic

Dan

40 years of experience
1080 reviews
Dan
40 years of experience
Plymouth Grand Voyager - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
 at YourMechanic

Christopher

9 years of experience
120 reviews
Christopher
9 years of experience
Ford Fiesta L4-1.6L - Check Engine Light is on - Smyrna, Georgia
Chris communicated with us each step of the way up until his arrival. He listened well, was knowledgeable, and was prepared. He took the time to diagnose the problem, explained the what, why and how and provided a solution. I would definitely recommend him and will use him again.


More related articles

Related questions

EVAP leak needs repairing.
Hi there, the code is a common one. The test procedure involves physically inspecting the canister for fuel. (https://www.yourmechanic.com/services/evaporative-emission-control-canister-replacement) The canister should only house fuel vapors not fuel. If no fuel is present then the purge valve needs to be...
ETC - 2008 Dodge Charger
Hello. The ETC code can come on for many reasons, but essentially the engine idle speed control is often times the problem. The fact that it indicated the spark plugs needed to be changed suggests there was a misfire of...
I think that my car has thrown a rod - 2006 Pontiac Torrent
Hi there. If you noticed a large hole on the side of the engine's block and it's leaking a lot of oil, it is highly likely that a connecting rod snapped and "windowed" the block. Unfortunately, there is no repair...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (844) 997-3624 · hi@yourmechanic.com