Faulty park/neutral safety switch or transmission range sensor (all sources; the Jeep manual names the transmission range sensor, GM the internal mode switch it is built into). Wiring problem: open circuit or short to ground in the park/neutral sense circuit (all sources). Range selector (shift) cable out of adjustment (GM manual). Corroded, damaged or pushed-out terminals at the PCM connector (Jeep manual). Faulty PCM (RepairPal and the Jeep manual, as a last step). The sources differ: RepairPal gives a short cause list, while the factory manuals add cable adjustment and connector checks and say to fix related transmission codes first.

Adjust the range selector cable. Repair an open or shorted park/neutral sense wire, or clean and repair connectors. Replace the park/neutral switch or transmission range sensor. Replace and program the PCM only after the switch and wiring test good (Jeep manual).

P0850🔧 Transmission / Park-neutral switchStop and fix promptly

P0850: Park/Neutral Switch Input Circuit (Meaning, Causes, Fixes)

Q: What does P0850 mean?

P0850 means the engine computer isn't getting a believable signal from the park/neutral switch, the switch that tells it the transmission is in Park or Neutral so the engine can be started. Common causes are a faulty switch (on many cars part of the transmission range sensor), an open or shorted wire, a misadjusted shift cable, or less often a faulty PCM. The powertrain control module (PCM) needs to know when the transmission is in Park or Neutral, because that is required before the engine can safely be started. RepairPal says the PCM relies on the park/neutral safety switch for this, and sets P0850 if the switch fails to operate properly; the engine may then be disabled from starting. The sources name the code slightly differently: RepairPal calls it Park/Neutral Switch Input Circuit, the 2007 Jeep factory service manuals call it Park/Neutral Switch Performance, and the Chevrolet Trax (2013-2022, 6T40 transmission) workshop manual calls it Park/Neutral Position Switch Circuit. They also describe different set conditions. On the 2007 Jeep Wrangler, Liberty and Grand Cherokee with a 4- or 5-speed automatic, the PCM runs a rationality test that checks whether the switch is stuck in the neutral position while driving, comparing vehicle speed, engine speed, throttle position and pressure ratio with the switch state; it is a two-trip fault, and the manual notes a switch stuck in drive isn't checked because the starter relay then won't energize and the vehicle won't start. On the Chevrolet Trax, the park/neutral switch is built into the transmission internal mode switch, and the ECM sets P0850 when the switch reads Park/Neutral (0 V) while the transmission reports Drive, with at least 10% throttle, at least 75 N-m of engine torque and at least 10 km/h (6 mph) for 0.2 seconds. Its sibling codes on that GM manual are P0851 (circuit low voltage) and P0852 (circuit high voltage). Exact tests and specs vary by make, model and transmission.

Q: Can I keep driving with P0850?

Stop and fix promptly. Get it diagnosed soon. RepairPal rates P0850 Urgent and says the engine may be disabled from starting, because the computer uses this switch to know the transmission is in Park or Neutral before it allows a start. The Jeep and Chevrolet factory manuals treat it as a switch-signal fault rather than a mechanical failure. Never bypass or jumper the park/neutral switch to get the car started: it is there so the engine can't crank while the car is in gear.

Reviewed 2026-10-24 · Based on 3 cited source(s)

What P0850 means

The powertrain control module (PCM) needs to know when the transmission is in Park or Neutral, because that is required before the engine can safely be started. RepairPal says the PCM relies on the park/neutral safety switch for this, and sets P0850 if the switch fails to operate properly; the engine may then be disabled from starting. The sources name the code slightly differently: RepairPal calls it Park/Neutral Switch Input Circuit, the 2007 Jeep factory service manuals call it Park/Neutral Switch Performance, and the Chevrolet Trax (2013-2022, 6T40 transmission) workshop manual calls it Park/Neutral Position Switch Circuit. They also describe different set conditions. On the 2007 Jeep Wrangler, Liberty and Grand Cherokee with a 4- or 5-speed automatic, the PCM runs a rationality test that checks whether the switch is stuck in the neutral position while driving, comparing vehicle speed, engine speed, throttle position and pressure ratio with the switch state; it is a two-trip fault, and the manual notes a switch stuck in drive isn't checked because the starter relay then won't energize and the vehicle won't start. On the Chevrolet Trax, the park/neutral switch is built into the transmission internal mode switch, and the ECM sets P0850 when the switch reads Park/Neutral (0 V) while the transmission reports Drive, with at least 10% throttle, at least 75 N-m of engine torque and at least 10 km/h (6 mph) for 0.2 seconds. Its sibling codes on that GM manual are P0851 (circuit low voltage) and P0852 (circuit high voltage). Exact tests and specs vary by make, model and transmission.

Severity: can I keep driving?

Stop and fix promptly

Get it diagnosed soon. RepairPal rates P0850 Urgent and says the engine may be disabled from starting, because the computer uses this switch to know the transmission is in Park or Neutral before it allows a start. The Jeep and Chevrolet factory manuals treat it as a switch-signal fault rather than a mechanical failure. Never bypass or jumper the park/neutral switch to get the car started: it is there so the engine can't crank while the car is in gear.

Common symptoms

Check engine light on
Engine may not start (RepairPal)
The Jeep manual notes the switch fault it checks for (stuck reading neutral while driving) may show no other symptom, while a switch stuck in drive leaves the vehicle unable to start
On the Chevrolet Trax, the ECM falls back to the gear position broadcast by the transmission control module for engine start-up (GM manual)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty park/neutral safety switch or transmission range sensor (all sources; the Jeep manual names the transmission range sensor, GM the internal mode switch it is built into)
Wiring problem: open circuit or short to ground in the park/neutral sense circuit (all sources)
Range selector (shift) cable out of adjustment (GM manual)
Corroded, damaged or pushed-out terminals at the PCM connector (Jeep manual)
Faulty PCM (RepairPal and the Jeep manual, as a last step)
The sources differ: RepairPal gives a short cause list, while the factory manuals add cable adjustment and connector checks and say to fix related transmission codes first

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes. The Jeep manual says to check the TCM for P0706 first and the Chevrolet manual says to check P182E or P1915 first; fix those before chasing P0850.
With the ignition on and engine off, watch the scan tool's park/neutral switch reading while slowly moving the shifter through every position. It should read Park/Neutral only in Park and Neutral.
Check that the shift cable is adjusted correctly, as the GM manual directs.
Inspect the wiring and connectors between the switch or range sensor and the PCM for damage, corrosion and loose or pushed-out pins.

Typical fixes

Adjust the range selector cable
Repair an open or shorted park/neutral sense wire, or clean and repair connectors
Replace the park/neutral switch or transmission range sensor
Replace and program the PCM only after the switch and wiring test good (Jeep manual)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The car won't start in Park or Neutral, or starts in gear
The Jeep manual's tests use a breakout tool so the PCM connector isn't probed directly; probing can damage its terminals
On the Jeep, the sense circuit should be grounded (below 10 ohms) in Park and Neutral and open (above 100 kohms) in other positions; the wire itself should read under 5 ohms end to end. Specs differ on other vehicles, so use your car's service data
On the Chevrolet Trax the switch is inside the transmission, so replacing it is a bigger job

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0850 serious?

It can be. RepairPal rates it Urgent because the engine may be disabled from starting. The switch also keeps the engine from cranking in gear, so get it fixed rather than bypassed.

Can I drive with P0850?

If the car starts and drives normally you can usually get it to a shop, but it may not restart. Don't bypass the park/neutral switch.

Is the park/neutral switch the same as the transmission range sensor?

On many cars it is part of it. The 2007 Jeep manual tests the P/N sense circuit of the transmission range sensor, and on the Chevrolet Trax the switch is built into the transmission internal mode switch.

What is the difference between P0850, P0851 and P0852?

In the Chevrolet Trax manual, P0850 is park/neutral position switch circuit, P0851 is circuit low voltage and P0852 is circuit high voltage.

How much does it cost to fix P0850?

None of the sources gives a repair cost. It ranges from a cable adjustment or wiring repair to a new switch or range sensor, so get a diagnosis and a written estimate first.

Sources

Last reviewed 2026-10-24. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.