neutral safety switch

Neutral Safety Switch Symptoms, Function & Replacement

In Electric by Magnus Sellén6 Comments

A neutral safety switch, as the name implies, is a safety purpose switch which is a common component found in vehicles with automatic transmission. These safety switches serve a simple purpose – limiting the vehicle from starting only in ‘Park’ or ‘Neutral’ gear.


What is a Neutral Safety Switch?

neutral safety switch

Unlike the manual transmission, the automatic transmission has no driver-operated clutch and no stick shift. In a manual transmission, a car can be started in any gear as long as the clutch is fully depressed but in case the clutch is not depressed and the car is in gear, trying to turn over the engine will cause sudden jerks as if the car is trying to go forward.

In either case, the car will start nonetheless but it can be dangerous as drivers can often forget that the transmission is in gear and accidentally turn the engine over, causing a jerk.
This is prevented in an automatic transmission using a neutral safety switch. This safety switch prevents the ignition from switching on at all when the car is in ‘Drive’ gear or ‘reverse’ or any other gear for forwarding. Even if the driver forgets to put the car in neutral or park, and cranks the engine, the engine won’t turn at all, preventing any hazard.
Sometimes this neutral switch can go bad causing starting problems.



Bad Neutral Safety Switch Symptoms

Figuring out whether a neutral safety switch has gone bad is relatively easy for someone with little knowledge about internal systems of a vehicle. Here are the symptoms to look for to diagnose your car’s neutral safety switch:

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The ‘check engine light’ lights up

If your engine light is up and you happen to have an OBD scanner, you can check for the code your car has given. If the code P084F comes up, it means your neutral switch is bad which should pretty much make the trouble code clear.

The car tries to startup in any gear

If you find out that your car’s engine is cranking even though it’s in ‘Drive’ or ‘Reverse’ or any other gear, it definitely means your car’s neutral switch is not working as it should since it shouldn’t be allowing the engine to turn over in any gear other than ‘Neutral’ or ‘Park’. That’s as far as your personal diagnostics can go because further inspections can only be made by a proper car mechanic with the right tools and accurate knowledge of automatic transmissions and their operations.

Car starts only in ‘Park’ but not ‘Neutral and vice versa

Although it’s better than the car starts at least in ‘Park’ and no in any other gear, the switch proves to be faulty in such a case and you should not overlook the situation, but get it checked asap by a certified mechanic because there’s no telling how long the neutral switch can go further so it’s better to get it fixed or changed before any major damage occurs.

The car starts sometimes, but sometimes don’t

If you face this problem that you are lucky your car starts sometimes, it is still possible that your neutral switch has either gone completely bad or failure is imminent. But in such a situation, the problem could be lying elsewhere too, like in the ignition itself, the starter, or the wiring. In any case, you’ll need professional help to resolve this issue. If you come to know that you are able to start your car after shifting the gear stick a couple of times before turning over the engine, then your neutral safety switch is the culprit.

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The engine doesn’t turn over at all

An engine not turning over at all could mean a lot of different things. From a bad battery to a faulty ignition and starter. You can check this by checking if the dash lights come on after turning the key half way. Unfortunately, for detailed inspection, you’ll need a professional to look into your car to determine the exact cause of the issue.


Testing & Solutions

Although there are a number of ways you can diagnose your car’s condition to a point, unfortunately, you won’t be able to perform any repairs or replacements yourself as accessing the neutral switch or ignition is difficult. You should consult a trusted or well-known mechanic to perform the diagnostics and repairs. A few things you could do to rule out other causes of the engine not starting:

Check Neutral Switch Parameters

You can check the parameters of the neutral switch to the ECM and Transmission control unit with an OBD2 scanner. Make sure the gear lever is correct and getting the right value of the desired gear.

Check your car’s battery

If your car doesn’t start even in ‘park’ or ‘neutral’, you could check if your battery is okay or not. The easiest way to determine is by checking the lights on your dashboard. If the lights come on, your battery should be okay. Always test to charge it first with a car battery charger.

Check your ignition

You should be able to hear a click when your turn key to crank the engine. If the click can be heard, your ignition is operating. If you hear no click and your engine doesn’t turn over, it could be the ignition although it’s better to confirm your doubts by going to a mechanic.

Check the engine’s starter motor

This can be a little difficult to check if you aren’t comfortable or don’t understand even the basic components of a car. But if you know enough, you could check your starter motor by putting your hand on the motor which is situated a bit deep inside the engine bay, beneath the engine block. If you feel any vibration whatsoever, your starter motor is working. You could also check it by using a voltmeter and checking the readings off of the starter’s terminals.
If none of these components are bad, then it’s highly probably your neutral safety switch has somehow gone bad and you’ll need a certified automatic transmission specialist to check the situation for you.

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Neutral switch Replacement Cost

Depending on the make and model of a vehicle, an estimated average cost of switch replacement goes range from $50 to $150. The labor cost can range from $50 to $100

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

  1. Thanks for the info! I kind of figured it was the problem while breaking it before pulling the transmission, due to needing a 3,4 clutch Pac! However my transmission problems became worse after the rebuild! It doesn’t want to move in any gear! Though I will check the amount of tranny fluid that is needed for my truck is what I’m hoping is the problem! For some reason my dipstick doesn’t sit all the way in, therefor making it impossible to get a reading!

    1. Author

      Thanks for your comment. There might be the wrong dipstick fitted in the car for that transmission? A faulty NSS can often cause the car to not engage any gears!

  2. Where is the neutral safety switch on a 2006 Mazda model 6,2.3 liter engine. Under the shifter when you remove the center console or under neath the vehicle in the front of the transmission.

  3. On the 2006mazda model 6 the car wouldn’t start sometimes unless you would jiggle it from left to right. Would nss be the culprit?

  4. So I have a 1994 CAD DeVille 4.9 engine had the starter checked have a brand new battery still the engine won’t turn over Iran codes current code says I 0 3 9 which I could not find in the codes website the engine, I hear the click for the ignition switch I don’t know what else to check can you please help me

  5. Due to a very high demand and high ammount of comments, you have to wait for some time for your car questions to get answered. If you want to get fast answers from a certified master technician you can ask your questions here:
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