P0850 on Nissan: park/neutral position (PNP) switch

TSS range switch for Nissan's JF011E CVT

In short

P0850 is stored by the engine computer, not the transmission computer: it means the park/neutral signal didn't change between starting and driving.
It shows up on manual and automatic cars: on manuals the signal comes from the gearbox's neutral switch, and on CVTs and automatics, from the range switch.
On the manual Versa and March, the same gearbox switch turns on the reverse lights; on the automatic Frontier, the signal goes through the instrument cluster.
Nissan assigns it no limp mode: it checks the fuse, the wire to the computer and the switch, and never opens the transmission.
It isn't the same as P0705: that one is stored by the transmission computer for the range switch circuit.

P0850 is one of the most-searched codes on Nissans in Mexico: Versa, March, Sentra, Tiida, Frontier and Urvan. It's stored by the engine computer, not the transmission computer, and it shows up on both automatic and manual cars. Here's what it means according to Nissan's service manual, where the signal comes from on each model, what Nissan checks and when it really is the switch.

What does code P0850 mean on a Nissan?

Nissan calls it "P0850 PNP SWITCH": the park/neutral position switch. Its manual defines it this way: the park/neutral signal didn't change between engine start and driving. The engine computer expects that signal on in P or N (in neutral, on manuals) and off while driving in gear; if it doesn't change, it stores P0850. On Nissan's scan tool, the data item to watch is "P/N POSI SW".

To confirm the code, Nissan drives with a warm engine above 64 km/h (40 mph) for 50 to 60 seconds. It uses its two-trip logic: the first time the code is stored without turning on the check engine light, and if the fault repeats on the next trip, the light comes on.

Where does the signal come from on your Nissan?

It depends on the transmission, the model and even the year. This is what Nissan's service manuals say, US editions unless noted:

Model	Where the park/neutral signal comes from
Manual Versa and March (2012 on)	From the position switch screwed into the transmission. On the Versa, that same 3-pin switch turns on the reverse lights and sends the neutral signal; removing it means draining the gearbox oil. The March uses the same gearbox.
4-speed automatic Versa and March	In the US 2013 Versa manual, which already covers this transmission, Nissan lists P0850 for the manual version only: on these automatics, a P0850 probably doesn't point to the range switch. Confirm it with a scan tool that reads the engine computer.
Sentra 2007 to 2012, X-Trail 2008 to 2014 and Altima 2.5 with a CVT	From the CVT's range switch, which has a separate output for the engine computer; the other goes to the transmission computer. For the Altima, Nissan has a diagnostic page written for Mexico.
Automatic Tiida	From the 4-speed's range switch, per the US 2011 Versa manual, which is the same platform.
Automatic Frontier V6	The signal goes from the transmission computer to the instrument cluster, and from there to the engine computer; that's why Nissan lists the cluster and the transmission computer among the causes.
Urvan NV350 and other manual models	The Urvan is sold only as a manual in Mexico; as on other manual Nissans, the signal should come from the gearbox's neutral switch (we didn't find its service manual).

P0850 symptoms

Nissan describes no driveability symptoms for this code:

Check engine light on, normally when the fault repeats on two trips.
It doesn't put the car in limp mode: in the 2012 Versa manual, P0850 isn't in the engine computer's fail-safe list.
The computer uses that signal for fuel injection, ignition timing and idle learning, which needs the lever in P or N (in neutral, on manuals).
On the manual Versa and March, if the reverse lights also fail, it points to the gearbox switch or its connector.

And if the car won't start? That's not the rule: on the Versa, cranking is controlled by the clutch pedal switch on manuals and the range switch on CVTs, not by the P0850 signal. On automatics, a failed range switch can cause both, since the same part has two circuits. More in our range switch guide.

What causes P0850?

The wiring or connectors: the signal circuit open or shorted.
The gearbox neutral switch, on manuals.
The range switch, on CVTs and automatics.
On the automatic Frontier, also the instrument cluster or the transmission computer.

Nissan doesn't replace or open the transmission for this code: its procedure checks circuits and, if the test fails, replaces the switch (or the cluster, on the automatic Frontier).

How is it diagnosed?

This is Nissan's order:

If several codes are set at once, P0850 is among the first Nissan says to check.
On the scan tool, "P/N POSI SW" should read ON in P or N (in neutral, on manuals) and OFF in every other position.
The switch's power feed: on the Versa, a 10 A fuse.
The signal wire to the engine computer: not open or shorted.
The switch: on manuals, continuity between its terminals only in neutral; on CVTs, the range switch test (the same as for P0705).
Only if it fails the test is it replaced.

Be careful with generic voltage rules: on the Versa, Sentra and Rogue (the X-Trail in Mexico) the computer sees battery voltage in P or N, but on the Frontier and Altima it sees about 0 volts. Use the value in your model's manual.

If you replace a CVT range switch, Nissan says to adjust it in N with a guide pin and check that the engine only cranks in P or N. We explain it in our range switch guide.

P0850 and P0705 aren't the same

P0850 is stored by the engine computer for the park/neutral signal; P0705 is stored by the transmission computer for the range switch circuit. On Nissan CVTs it's the same part with different terminals, and manuals have no P0705. More on each model's transmission in What transmission does my Nissan have?.

P1706: the same code on older Nissans

On older Nissans the same check has another number: in the US 2003 Altima manual, Nissan calls it "P1706 PNP SWITCH", with the same park/neutral switch description and the same "P/N POSI SW" scan item. Note: on Hondas, P1706 is a different code, range switch open.

Can I keep driving with P0850?

Nissan assigns no limp mode on the Versa and describes no driveability symptoms, but it's worth checking soon: the computer uses that signal for fuel injection, ignition timing and idle learning.

TSS parts

TSS has the range switch for the JF011E CVT with the 90° connector. For the Versa, March, Tiida, Frontier, Urvan and NP300 there's no TSS switch: in those cases, check the gearbox switch, the wiring and the connector, as Nissan does.