Car starts in On position

My car starts when the key in the On position, but it should only start in Start position.
Experienced mechanics share their insights in answering this question :
The most likely cause of this issue is a faulty ignition switch or lock cylinder. One of the tumblers may have fallen out of place causing a connection to the starter when there should not be. My best recommendation would be to have your ignition switch tested for faults by a qualified technician. If the switch requires replacement, a new key will also come with the switch and that will be your new ignition key. I would only recommend having the ignition switch replaced by a professional, as accidental cranking of the starter during replacement of the ignition switch could hurt someone.

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The most likely cause of this issue is a faulty ignition switch or lock cylinder. One of the tumblers may have fallen out of place causing a connection to the starter when there should not be. My best recommendation would be to have your ignition switch tested for faults by a qualified technician.
The ignition switch has four positions: LOCK (0), ACCESSORY (I), ON (II), and START (III). Use this position only to start the engine. The switch returns to the ON (II) position when you let go of the ignition switch.
The ignition switch sends power to the starter motor, engine controls, and ignition controls.
Sometimes a bad starter solenoid, instead of preventing the engine from starting, may cause it to start on its own without the key being turned to the “start” position.” This less-common problem can be dangerous and should be addressed immediately.
Conventional 3 positions are off, run, and start.
Ignition switch

The switch has 5 positions, which are: OFF, R, L, BOTH, START. R and L stand for right and left, if that needed to be clarified.

The location of the start relay varies by vehicle type and model. The fuse box (also called the power box), the instrument panel under the fuse panel, or the right fender are all possible locations. In most cars, it will be under the hood, in a large box with a black lid.
When you switch on the ignition key, a starter relay transmits small electric power to the starter solenoid, while the solenoid pulls a big current straight from the car batteries. This activates the solenoid, which sends electricity to the starter motor, which spins the flywheel.
The ignition relay is one of the most important electronic relays found on modern vehicles. It is usually located in the fuse and relay panel beneath the bonnet, and is responsible for providing power to the vehicle`s ignition system, and some of the fuel system`s components.
A sticking or worn-out key cylinder or a problem with the starter interlock switch can cause the engine to stay running after the ignition is turned off. A fault in the car`s body control module (BCM) or engine control module (ECM) can also cause the engine to stay running after the ignition is turned off.
This is usually a sign of a faulty starter solenoid. There are a few wires that connect to the starter solenoid coming from the battery, the starter, and the ignition switch.
Auto Start-Stop can be temporarily disabled. To turn the system off, press the Auto Start-Stop Off button on your instrument cluster. Note: This is not a permanent change, you will have to deactivate it each time you start your vehicle.
This is usually a sign of a faulty starter solenoid. There are a few wires that connect to the starter solenoid coming from the battery, the starter, and the ignition switch.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My car will not start Intermittently. I purchased a new battery 2 weeks ago and yesterday the car wouldn’t start. Got a jump and
ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Map sensor car won’t start up good ?
ANSWER : Your MAP sensor is an important input for your computer. It helps determine the load on the engine to calculate the correct amount of fuel to inject. It sometimes takes a few seconds for the vehicle to realize that the sensor is not producing a good signal.

At that point, it will use other methods to determine the fuel rate, such as pre-programmed fuel maps, throttle position, etc. I would suggest replacing the MAP sensor and retesting. If you would like to have it checked first, a certified technician from YourMechanic will be able to scan your vehicle and test components to determine the root cause of your starting issue before making a repair.

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car hesitates when trying to start the car ,but when started then i shut car off and start again it will start right up
ANSWER : Hi there:

Sometimes when you have problems starting an engine initially it is caused by a restriction in fuel flow; caused either by clogged fuel injectors or the throttle body that needs to be cleaned. Once the fuel starts to flow and engine warms up, it’s much easier to start. However, it could also be an air filter, EGR valve or other components that causes this issue as well, which is why it’s best to have a professional mobile mechanic complete a car is hard to start inspection so they can pinpoint the source of this issue.

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When I go to crank my car the key stays in the start position and the car is constantly trying to crank itself.
ANSWER : First, let’s make sure about some terminology before I proceed. I will assume the motor is actually turning over. If the car is trying to start, the motor has to be turning over or it is not trying to start. This is an important distinction when diagnosing the starting system. As a technician, I go to different parts of the system based on this description.

If the key is stuck in the start position, this is a ignition lock cylinder issue and the reason the starter continues to turn the motor over. If the starter is turning but the motor is not, then the starter is likely the problem. Either that or the teeth on the flex plate are all gone. This would require removing the transmission to repair.

If the car runs intermittently, this can be a big challenge. And it also means the starting system is working. It will need to be diagnosed when it is failing. A working car cannot be diagnosed because there is nothing wrong. Where you park your car should not have any affect. It certainly could be a wiring problem. Wiring problems hide really well and can happen anywhere in the miles of wires that are in your car. Isolating the system that is failing is really important here. At the moment I am unsure which system is failing. Starter system, ignition lock cylinder and or ignition switch electrical or something with the engine control system.

When the car is failing, you need to check for spark and fuel pressure. If neither is present, this is a clue. Usually the crank sensor will do this. Does your car have a tachometer? If so, does it move at all when cranking. This is a clue whether or not the cam and or crank sensor is working. Is there a Check Engine Light on with the key on? If there is a Check Engine Light, the code or codes can be used for specific diagnosis.

All of these concerns will send you down a diagnostic path. Be sure not to confuse yourself by misinterpreting multiple system failures. If the key does stick in the start position, this would be the first problem to solve. After that, does the motor actually turn when the starter turns? After that, the question of "Why won’t it start?" is first answered by finding what the motor is lacking. Fuel, spark etc… Good luck.

If you need assistance with these checks, contact a certified mechanic who has the tools and experience needed to properly diagnose this starting issue with your car.

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My car will be starting perfect and when the gas tank gets lower it will start having problems .
ANSWER : Based on the information you gave, it sounds like a possible fuel starvation issue, caused by a partially blocked, in-tank fuel filter or a crack in the fuel pump housing. The remedy would be to replace the fuel pump assembly and filter. The overheating may be caused by several things, including a stuck thermostat, faulty water pump, or even a cracked head gasket. I suggest having a certified technician, like one from YourMechanic, inspect the relevant systems to pinpoint the cause of your vehicle’s hard starting issue and overheating problem.

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My car stutter starts, but only after driving it for a few minutes.
ANSWER : Hey there. This may also be caused by what is called the fuel pressure regulator. This is a unit that helps to maintain the fuel pressure at the proper level. When this is not working properly, the fuel pump may be pumping properly, but the fuel may not arrive at the fuel injectors at the proper psi. When this happens, this can cause a lean fuel condition which may cause the car to hesitate, misfire, or stall. If you would like to have an expert pinpoint the issue, a certified professional from YourMechanic can come to your car’s location to inspect the hard start problem and confirm which repairs are needed.

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2005 Chrysler 300C changed battery and alternator. Car started, ran, and then battery light came on. Shut car off and wouldn’t start.
ANSWER : Hi. There is a couple of things that could be wrong here. The battery or alternator that was just installed could be defective. Theses parts need to be tested for proper operation. There also could be a fuse, fusible link, or wiring for the battery or charging system that is blown or broken causing the battery light to come on.

The codes that you have will cause the car to shut down, run rough, or not start at all. The crankshaft sensor and camshaft sensor should be replaced. I suggest having a certified technician from YourMechanic come diagnose the charging system and check engine codes to help you proceed with correct repairs.

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Charging warning light comes on when i turn the key and try to start the car and the car want start but when someone tried to give
ANSWER : Hi there:

If you recently replaced your battery, the issue may be caused by a malfunctioning alternator or other electrical component that comprises the charging system on your Nissan Sentra. The best way to find out which item specifically is faulty, is to have a professional mobile mechanic complete a car is hard to start inspection. This will allow the mechanic to determine the precise source of what’s going on with your Sentra and recommend or complete the right repairs.

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