Key Takeaways
- Check the Fob Battery First: It is the #1 cause of failure. If the little light on your remote doesn't flash, swap the battery.
- Look for a Check Engine Light: Most cars disable remote start if there is an active engine warning code.
- Hood Latch Safety: If the car thinks the hood is open (due to a bad sensor), it wont start to protect mechanics.
- Valet Mode: Check if your system was accidentally put into "Valet Mode," which disables the remote start feature.
- Maximum Attempts: You usually only get two remote starts before you actually have to put the key in the ignition.
The Short Answer: Why It isn't Working
If your remote start isn't working, the problem is usually your key fob battery, a "Check Engine" light on your dashboard, or a faulty hood latch sensor. Before you panic and call a tow truck or the dealership, try changing the battery in your remote (usually a CR2032 coin battery). If that doesn't fix it, go out to the car, start it manually, and see if there are any warning lights on the dash. If the car thinks something is wrong with the engine, it disables the remote start to prevent damage.
Now, lets dig into the nitty-gritty details so we can get your car warm (or cool) again.
1. The Key Fob Battery is Dead (Or Dying)
I know this sounds obvious, but you would be surprised how many people overlook this. It is the simplest fix and definitely the most common issue. Even if the battery still has enough juice to unlock the doors, it might not have the strong signal burst required to send the remote start command, especially from inside your house.
Most remotes use a little coin-style battery. You can usually pop the remote open with a flathead screwdriver or even a butter knife if you're careful. If you have a voltmeter, check the voltage. If it is under 3 volts, it’s toast. If you don't have a meter, just spend the $5 and swap it out.
Pro Tip: Many 2-way remotes (the ones with LCD screens) allow you to recharge them. If you have one of those fancy aftermarket ones like Viper or Compustar, check if it needs a USB charge.
2. The "Check Engine" Light is On
This is a safety feature that confuses a lot of people. Modern cars are smart. Like, really smart. If the vehicle's computer (the ECU) detects a problem, it triggers the Check Engine Light (CEL). When that light is on, the car goes into a self-preservation mode.
According to most manufacturer manuals, the system disables remote start because it doesn't want the engine running without a driver present to monitor it. Imagine if you had a major oil leak or an overheating issue; remote starting it could destroy the engine while you are finishing your coffee in the kitchen.
If you start the car manually and see that orange engine icon, you need to get the code read. Once you fix the issue and clear the code, your remote start should work again immediately.
3. The Hood Pin Switch is Broken or Corroded
This is a massive issue with aftermarket systems, but it happens to factory ones too. There is a safety switch under your hood-usually a little plunger that gets pushed down when the hood closes. This is there to ensure that if a mechanic is working on the engine, you don't accidentally remote start the car and chop their fingers off with the fan belt.
If that switch is broken, bent, or rusty (which happens a lot because of road salt), the car thinks the hood is open. If the car thinks the hood is open, it refuses to start.
How to test this:
- Open your hood.
- Find the switch (usually along the edge of the engine bay).
- Press it down with your finger.
- Have a friend try to remote start the car.
If it starts while you are holding the button down, you know the switch is the problem. You might just need to bend the bracket up a little bit so the hood hits it harder.
4. You're in "Valet Mode"
I’ve done this myself and felt pretty silly afterwards. "Valet Mode" is a setting that disables the alarm and remote start features so that a valet driver doesn't accidentally set off your alarm or mess with your settings.
If you have an aftermarket system, you might have triggered this by accident. Sometimes it happens if you press a specific combination of buttons on the remote, or if you toggle a switch under the dashboard. Usually, on systems like Viper, the parking lights will allow you to know. If the LED light on your antenna (on the windshield) stays solid blue or red without blinking, you might be in Valet Mode.
To fix this, you usually have to turn the ignition on and off and tap the "valet button" (a hidden little black button under your dash) a specific number of times. You'll have to Google your specific alarm model for the exact sequence.
5. The Car is Not in "Park" (or Neutral Safety Switch)
This is strictly a safety thing. The remote starter will not engage if the car isn't fully in Park. Sometimes, the gear shifter cable gets a little loose, and even though the shifter looks like it's in "P", the sensor down in the transmission doesn't think so.
Try this: Go to the car, push the shifter firmly into Park, maybe even wiggle it a bit, and then try the remote start again. If you drive a manual transmission (stick shift), the procedure is way more complex. You usually have to follow a "reservation mode" sequence (neutral, parking brake up, foot off brake, remove key, exit car) to prove to the system that the car is in neutral. If you opened a door after setting that up, the system cancels the remote start to prevent the car from lunging forward.
6. You Have Exceeded the Maximum Starts
Did you know there's a limit? Most factory remote starts (like on Fords, Chevys, and Toyotas) only allow you to remote start the vehicle twice in a row.
Let's say you started it, let it run for 10 minutes, and it shut off. Then you started it again, but got distracted and it shut off again. If you try a third time, it simply won't work. The manufacturer programs this to prevent carbon monoxide buildup if you accidentally start the car in a garage, and to save fuel.
To reset this counter, you just have to go out to the car, insert the actual key (or push the start button), turn the ignition fully on, and then turn it off. That resets the cycle.
7. The Main Car Battery Voltage is Low
Remote start systems are tough on batteries. In the winter-which is exactly when you want to use the remote start-batteries are at their weakest. If your car battery voltage drops below a certain threshold (usually around 11.5 or 12 volts), the remote start brain will abort the start attempt.
It takes a lot of amperage to crank a cold engine. If the system detects the battery is weak, it might flash the parking lights at you but refuse to crank the starter. It does this so there is hopefully enough power left for you to go out and start it manually with the key. If your car is cranking slower than usual, it’s time to get that battery tested at an auto parts store.
8. Coolant or Oil Pressure Issues
Some newer vehicles have sensors that monitor oil pressure and coolant temperature specifically for the remote start sequence. If the car starts but doesn't see oil pressure rise immediately, it cuts the engine to save it. Similarly, if the temperature sensor is reading something crazy (like -40 or +300 degrees due to a bad wire), the system wont engage.
This is harder to diagnose yourself. If the car starts for 2 seconds and then shuts down immediately, this is likely the cause. The system tried, saw a "danger" signal, and killed the engine.
9. Door or Trunk Pins are "Open"
Just like the hood pin, the car monitors the doors and trunk. If your dashboard says "Door Ajar" or "Trunk Open," the remote start will not work.
This is a security feature. If a thief has pried your door open, the car doesn't want to let you remote start it (which might unlock the ignition circuit). Double-check that all doors are slammed shut. Sometimes a seatbelt gets caught in the door jamb, preventing it from closing that last millimeter needed to satisfy the sensor.
10. Hazard Lights are On
This is a weird one, but I've seen it happen. On some vehicles, if the hazard lights (flashers) are on, the remote start is disabled. I'm not entirely sure why engineers do this, maybe it assumes the car is in distress? Regardless, make sure your flashers are off.
Troubleshooting Checklist: Step-by-Step
If you are standing in your driveway freezing, here is the order of operations I would follow to fix this:
- Swap the remote battery. It's cheap and easy.
- Check the brake lights. Wait, what? Yes. If your brake light switch is stuck "on," the remote start thinks you are pressing the brake pedal. Pressing the brake pedal shuts down the remote start. Have someone stand behind the car while you don't touch anything. Are the brake lights on?
- Sit inside and listen. Get in the car, lock the doors with the remote, and try to remote start it while sitting in the driver's seat. Listen to the clicks. Does the dash light up? Does the fuel pump hum? This tells you if the signal is getting to the car.
- Count the flashes. Most remote start systems communicate via the parking lights. If it fails, the parking lights usually flash a code. For example, on a Compustar system, 7 flashes might mean "Manual Transmission Mode Error." Look up the flash codes for your specific brand online.
- Reset the system. Sometimes, just disconnecting the negative terminal of your car battery for 15 minutes can reset the computer logic and clear out gremlins. Just be aware you'll lose your radio presets.
Aftermarket vs. Factory Systems
It's important to distinguish between the two because they break in different ways.
Factory Systems (OEM)
These are built into the car's computer. They are very reliable but also very sensitive to safety sensors. If *any* check engine light is on, they fail. They rarely have wiring issues because the wiring is part of the car's original harness. The range is usually shorter, so if you are too far away, that's your problem right there.
Aftermarket Systems (Viper, Python, etc.)
These are installed by humans, usually splicing wires under the dash. Over time, T-taps (the plastic clips used to connect wires) can wiggle loose. Ground wires can rust. If your system is aftermarket and it suddenly stops working, it is often a loose connection or a blown fuse on the remote start module itself.
Also, aftermarket systems often have an "Antenna" on the windshield. If the cable going to that antenna gets pinched or cut, you lose all range.
Final Thoughts
Honestly, 9 times out of 10, when a friend asks me this, I tell them to go change the battery in the fob, and they look at me like I'm a wizard when it works. If it's not that, check for that pesky Check Engine Light.
Remote starters are luxuries, but once you have one, you really can't live without it. Hopefully, this guide helped you track down the issue so you aren't shivering in your seat tomorrow morning!
Frequently Asked Questions
Can a weak car battery cause remote start failure?
Absolutely. If the car battery voltage is too low to crank the engine safely, the remote start brain will cancel the attempt to prevent the battery from dying completely.
Why does my car start then shut off immediately?
This usually means the remote start "Tachometer Signal" is lost. The system starts the car, but doesn't "know" the car is running, so it cuts power to prevent the starter motor from grinding. It could also be a security immobilizer issue where the car key chip isn't being read correctly.
Does the Check Engine Light disable remote start?
Yes, on almost all modern factory systems. It is a safety precaution to prevent engine damage.
Where is the valet switch located?
On aftermarket systems, it is usually a small toggle switch or a push button located under the driver's side dashboard, near the kick panel, or sometimes on the antenna on the windshield.
How much does it cost to fix a remote start?
If it's just a battery, $5. If it's a hood pin, maybe $20 for the part. If it is an electrical wiring issue or a bad module, you might be looking at $100-$300 at a car audio shop.