Key Takeaways
- Dead Fob Battery: The #1 culprit. If the light on your remote is weak or doesn't flash, swap the battery (usually a CR2032).
- Check Engine Light: Most cars automatically disable remote start if the Check Engine Light is on to protect the engine.
- Hood Pin Switch: If the car thinks the hood is open (even if it isn't), it won't start for safety reasons.
- Valet Mode: You might have accidentally triggered a mode that disables the system.
- Door/Trunk Ajar: If a door isn't closed all the way, the system usually refuses to fire up.
The short answer is usually your key fob battery is dead or your car is in "Valet Mode." If you press the button and the little LED light on the remote doesn't flash, or it flashes weakly, go buy a CR2032 battery for five bucks and swap it out. If the remote light works but the car doesn't respond, check your dashboard. Is the "Check Engine" light on? If yes, the car is disabling remote start on purpose to save itself from damage.
But honestly, there is alot more that goes into these systems than people think. Whether you have a factory system that came with your Ford or Chevy, or an aftermarket one like Viper or Compustar, the logic is pretty similar. I’m gonna walk you through exactly why this happens so you aren't stuck freezing in your driveway tomorrow morning.
The Most Common Culprit: The Key Fob
I know I mentioned this already, but we have to start here because 90% of the time, this is it. These remotes take a beating. We drop them in puddles, sit on them, and toss them on the counter.
Battery Issues
Most remotes run on coin-cell batteries. Even if the light flashes, it might not have enough "juice" to send the signal all the way to the car, especially if you are trying to start it from inside the house. Cold weather actually drains batteries faster too, which is ironic because that's exactly when you need the remote start the work.
If you have a 2-way remote (the kind that beeps back at you or has an LCD screen), those batteries die way faster than the basic ones. Try holding the remote up to your chin-I know it sounds crazy, but the fluids in your head act like an antenna and can extend the range slightly. If it starts when you're close but not when you're far, change the battery.
De-programming
Sometimes, if the battery dies completely and stays dead for a while, the remote forgets who it belongs to. It loses its pairing with the car. You might need to look up the reprogramming sequence for your specific alarm model. Usually, it involves turning the key in the ignition a few times and pressing a button on the remote.
Safety Switches: The Car Is Protecting You
If your remote has fresh batteries and the car still wont start, the problem is likely a safety sensor. Remote starters are designed with a ton of kill-switches. The manufacturers, like Toyota or Honda, are terrified of lawsuits, so if anything looks unsafe, the system shuts down.
The Hood Pin Switch
This is probably the most annoying failure point. Under your hood, there is a small pin or a tilt switch. Its job is to tell the car if the hood is open. Why? Because if a mechanic is working on your engine and you accidentally remote start it from the waiting room, their hands could get mangled by the fan belt.
The problem is, these switches get dirty, rusty, or bent. If the switch thinks the hood is open, the remote start will not work. Sometimes the bracket holding the switch gets bent down, so when you close the hood, it doesn't push the button all the way.
Quick fix: Find the switch (usually along the edge of the engine bay), press it down with your thumb, and have a friend try the remote start. If it fires up, you know you need to adjust or replace that pin.
Door and Trunk Sensors
Just like the hood, if a door is slightly ajar or the trunk isn't slammed shut, the system refuses to start. It’s a theft deterrent and a safety measure. Make sure your dashboard doesn't show a "Door Open" warning.
The Brake Pedal
Most systems are wired to the brake pedal. If you step on the brake before putting the key in the ignition (or pressing the start button inside), the engine kills immediately. But sometimes, a faulty brake light switch can trick the system into thinking the brake is being pressed even when the car is empty. If your brake lights are flickering or stuck on, your remote start definitely won't work.
The Check Engine Light (CEL)
This is a big one that people forget. According to most factory manuals, remote start is disabled if the Check Engine Light is illuminated.
The logic is pretty sound: If the car has an engine problem, running it without a driver present to hear strange noises or see smoke is a bad idea. The computer (ECU) puts the car in a safety mode.
The annoying part is that a CEL can be caused by something super minor, like a loose gas cap. I remember one time my truck wouldn't remote start for a week just because the EVAP sensor was dirty. No mechanical damage, but the computer didn't know that. If you see that yellow engine light on your dash, you need to get the code read and cleared before the remote start will work again.
Valet Mode
If you have an aftermarket system (like Viper, Clifford, or Avital), you might be in "Valet Mode." This is a mode designed for when you hand your keys to a parking attendant. It allows them to lock and unlock the car, but disables the alarm and remote start so they don't accidentally set it off.
How do you know? Look at the LED light on your dashboard (the antenna blinker).
- If it's solid blue or red without flashing, you are probably in Valet Mode.
- If it doesn't light up at all when you lock the car, you might be in Valet Mode.
People accidentally enter this mode all the time by pressing a combination of buttons on the fob. To get out of it, the process varies. A common method for many systems is to turn the ignition on and off, then press and hold the valet button (a hidden little black button under the dash) for a few seconds. You might hear a chirp, and then you're back in business.
You've Hit the "Start Limit"
Did you know there is a limit to how many times you can remote start the car in a row? Most factory systems only allow two remote start cycles (usually 10 or 15 minutes each). After that, the car says "Enough."
They do this to prevent carbon monoxide buildup if you accidentally start the car in a garage, and to stop you from draining the gas tank completely. If you have already started it twice to warm it up, you have to physically go out, insert the key (or push the start button), and reset the cycle.
Environmental Factors
Sometimes, it's just too cold. I know, I know-that defeats the purpose. But hear me out.
If the temperature drops way below zero, your car battery voltage drops significantly. The remote start module needs a specific voltage to trigger the ignition sequence. If the battery is sitting at 11.5 volts because it's freezing out, it might not have enough kick to engage the starter, even if the lights turn on.
Also, older diesel trucks often have a "Wait to Start" delay for the glow plugs. If an aftermarket remote start wasn't programmed correctly to wait for that delay, it tries to crank immediately, fails, and gives up.
Technical Glitches (The "Tach" Signal)
This is getting a bit into the weeds, but if you recently had your battery disconnected or your car serviced, the remote start might have lost its "Tachometer Signal."
The remote start brain needs to know when the engine is actually running so it knows when to stop cranking the starter. It usually monitors the RPMs (tachs). If it loses that memory, it might crank for half a second and stop, or not crank at all because it's confused.
For many aftermarket systems, you have to re-learn the tach signal. It usually involves starting the car with the key, holding the foot brake, and holding a button on the remote starter antenna until the light flashes. If you aren't comfortable doing this, take it back to the shop that installed it. It usually takes them about 30 seconds to fix.
Oil and Coolant Pressure
Modern cars are incredibly smart computers on wheels. Some systems monitor oil pressure and coolant temperature during the remote start sequence.
If the car starts but then shuts off after 5 or 10 seconds, this is usually the cause. The system fires the engine, checks the oil pressure, and if the sensor is reading low (which happens when oil is thick and cold), it kills the engine to save it. It's frustrating, but it's better than blowing a piston.
Coolant Temperature Sensor
Conversely, if the car is already warm, some systems won't remote start. I had a friend with a Chevy who tried to show off his remote start just after we parked at the mall. It wouldn't work. Why? Because the engine was already at operating temperature. The car's computer decided, "I'm already warm, I don't need to idle," and blocked the request. It’s rare, but it happens.
Subscription Services
We are moving into an era where everything is a subscription. If you use a phone app to start your car (like DroneMobile, Viper SmartStart, OnStar, or FordPass), check your billing.
It sounds silly, but if your credit card expired last month, they might have cut your service. These systems rely on cellular data (AT&T or Verizon networks usually). If the bill isn't paid, the signal never gets to the car. Also, if your car is parked in a deep underground garage, it might not have cell service, meaning the app won't work even if the key fob would.
On/Off Toggle Switch
Some cars have a physical toggle switch to disable the remote start. On older aftermarket installs, installers would put a small toggle switch under the dashboard or near the kick panel. This is a "Master Kill Switch" for the system. If you kicked it with your foot while driving, you might have turned the whole system off. Get a flashlight and look under your dash for any mysterious toggle switches.
For factory systems, this setting is usually in the instrument cluster menu. Go into your car's settings on the dashboard screen, look for "Vehicle Settings" or "Comfort and Convenience," and make sure "Remote Start" is actually checked "ON." Sometimes a dead car battery can reset these settings to factory defaults (which might be OFF).
Summary of Troubleshooting Steps
If I were standing there with you, here is the order I would do things in:
- Change the remote battery. It's the cheapest and easiest fix.
- Walk around the car. Ensure all doors, hood, and trunk are fully closed.
- Check for Dashboard Lights. Start the car manually. Is the Check Engine Light on? If so, that's your problem.
- Check Valet Mode. If your LED is solid, look up how to exit Valet Mode for your brand.
- Listen. When you press the button, do the parking lights flash? Do you hear clicks under the hood?
- Lights flash but no crank: Usually an issue with the bypass module (immobilizer) or a blown fuse.
- Cranks but won't start: Could be fuel, spark, or tach signal issue.
- Nothing happens at all: Dead remote or the receiver in the car is unplugged/broken.
Don't be afraid to consult the manual. I know, nobody reads the manual, but the troubleshooting section for remote starters is usually only one page and it can save you a trip to the mechanic.
Frequently Asked Questions
Can a low car battery prevent remote start?
Absolutely. Even if the car has enough power to unlock the doors, the remote start system monitors voltage. If the voltage is too low (usually below 11.5 volts), the system aborts the start to ensure there is enough power left for you to start it manually with the key.
Does the Check Engine Light disable remote start on all cars?
Not all cars, but most modern ones (post-2010 usually). Factory systems almost always disable it. Aftermarket systems (like Viper) might still force the car to start depending on how they were installed, but even they are getting smarter about reading engine codes.
Why does my car start, run for 5 seconds, and then turn off?
This is usually a "Tach Signal" failure. The remote starter doesn't realize the engine is running, so it shuts down to try again. It could also be the car's immobilizer (anti-theft) kicking in because it didn't recognize the bypass signal.
How much does it cost to fix a remote start?
If it's just a battery, $5. If it's a hood pin switch, maybe $20 for the part. If the "brain" of the remote start is fried or the wiring is corroded, you might be looking at $100-$300 for a shop to rewire or replace the module.
Can I reset my remote starter myself?
Yes, often by disconnecting the negative terminal of your car battery for about 15 minutes. This acts as a hard reboot for all the electronics in the car. Just be aware this will also reset your radio presets and clock!