Key Takeaways
- It’s a Safety Feature: Your remote start is likely fine. Most modern cars automatically disable remote start when the Check Engine Light (CEL) is on to prevent engine damage.
- Check the Gas Cap: The most common, easiest fix is a loose gas cap. Tighten it and drive for a few days to see if the light clears.
- Scan the Codes: You need an OBDII scanner to know exactly whats wrong. Auto parts stores will usually do this for free.
- Clear the Code: The remote start won't work again until the check engine light is turned off or the code is cleared from the computer.
The Short Answer: Why Your Remote Start Stopped Working
If your check engine light is on, your remote start is disabled on purpose. It is not a glitch.
Most manufacturers-especially GM (Chevy, GMC, Cadillac), Ford, Toyota, and Honda-program the car's computer to shut down the remote start system the second a "fault code" is detected. The logic is actually pretty smart: if the computer thinks there is something wrong with the engine, it doesn't want the car idling in your driveway without you sitting in the driver's seat to watch the oil pressure or temperature gauges.
So, to fix your remote start, you don't need to look at the key fob or the starter motor. You have to fix whatever is causing the check engine light. Once that light turns off, your remote start will work again immediately.
Here is everything you need to know to get this fixed, starting with the cheap and easy stuff first.
Step 1: The "Gas Cap" Trick (Do This First)
Before you go spend money at a mechanic or start panicking that your transmission is blown, check your gas cap. Honestly, this is the cause like 40% of the time.
Modern cars have sensitive "EVAP" systems. These systems capture gas fumes so they don't pollute the air. If your gas cap is loose, cracked, or simply wasn't tightened enough the last time you filled up, the system detects a leak. It triggers the Check Engine Light.
Here is what to do:
- Go to your car and unscrew the gas cap.
- Inspect the rubber seal (the O-ring) inside the cap. Is it cracked? Is it dirty? If it looks bad, buy a new one for $15 at an auto parts store.
- If it looks okay, screw it back on until it clicks. Most caps need one good click, but some older ones need three.
Important: The light won't go off immediately. You usually have to drive the car for a few "cycles" (turning it on, driving for 10-15 minutes, and turning it off). It might take a day or two for the computer to re-check the system, realize the leak is gone, and turn off the light. Once the light goes off, try your remote start. It should work.
Step 2: Get the Code Scanned
If you tightened the cap and drove around for a few days and the light is still staring at you, you have to find out what the computer is complaining about. You need the "Error Code."
You have two options here, and both are pretty easy.
Option A: Go to an Auto Parts Store (Free)
Places like AutoZone, O'Reilly's, or Advance Auto Parts will almost always scan your car for free. Just walk in and say, "Hey, my check engine light is on, can you check the code for me?"
They will plug a little handheld computer into a port under your dashboard. It takes about 30 seconds. They will give you a code that looks like P0420 or P0301. Write that code down!
Option B: Buy Your Own Scanner (Cheap)
If you don't want to talk to anyone, you can buy a cheap OBDII scanner on Amazon for like $20. It connects to your phone via Bluetooth. It is a super handy tool to have in your glovebox anyway.
Common Codes That Kill Remote Start
Once you have the code, you can figure out what is actually broken. Here are the most common culprits I see that disable the remote start feature.
P0440 / P0442 / P0455 (EVAP System Leaks)
These are the "fume leak" codes. As we talked about earlier, this is usually the gas cap. But if a new gas cap doesn't fix it, it could be a small part called a Purge Valve or a Vent Solenoid. These sound complicated but they are usually cheap plastic parts that are easy to swap out.
P0300 - P0308 (Cylinder Misfire)
This means one of your engine cylinders isn't firing correctly. It usually feels like the car is shaking or running "rough" when you are stopped at a red light.
The Fix: Usually spark plugs or ignition coils. If you haven't changed your spark plugs in 100,000 miles, its time. This is a standard maintenance item. Once you change the plugs, the engine runs smooth, the light goes off, and your remote start comes back.
P0171 / P0174 (System Too Lean)
This means the engine is getting too much air and not enough fuel. This is often caused by a dirty Mass Air Flow (MAF) Sensor.
The Fix: You can buy a can of "MAF Sensor Cleaner" for $8. You take the sensor out (usually just two screws on the air intake tube), spray it clean, let it dry, and put it back. It’s a super satisfying 10-minute DIY job.
P0420 (Catalytic Converter)
This one hurts the wallet a bit more. It means your catalytic converter (the part that cleans exhaust) isn't working efficiently. This is common on older cars with high mileage.
Sometimes you can try a fuel additive "catalytic converter cleaner" (like Cataclean) to see if it clears the gunk out enough to turn the light off. If that works, you saved yourself a thousand bucks.
Step 3: Resetting the Computer (The "Hard Reset")
Let's say you fixed the problem-you replaced the gas cap or changed the spark plugs-but the light is still on. Sometimes the car's computer is stubborn and holds onto the memory of the old problem.
You can try a hard reset to force the light off and get your remote start back. Here is how you do it safely.
The Battery Disconnect Method:
- Pop the hood and find your car battery.
- Take a wrench (usually 10mm) and loosen the bolt on the Negative (Black) terminal. Do not touch the Red positive one.
- Pull the black cable off the battery post.
- Wait about 15 to 20 minutes. Go grab a coffee. This drains the residual power from the car's computer modules.
- Reconnect the black cable and tighten it up.
What happens next?
When you start the car, the check engine light should be gone. Now, turn the car off, lock the doors, and try your remote start. It should fire right up!
Warning: This will also reset your radio presets and maybe your clock. It's annoying, but it works. Also, if you didn't actually fix the problem (like if that sensor is still broken), the light will come back on after you drive 50 miles, and the remote start will stop working again.
Why Do Manufacturers Do This?
I know it feels like the car company is punishing you. You pay for a feature, you want to use it, right?
But imagine this scenario: You have a massive oil leak or your engine is overheating rapidly. The car throws a check engine light to warn you. If you were driving, you’d see the warning and pull over. But if you remote start the car from your kitchen, the car is running for 10 or 15 minutes with zero oil pressure while you finish your breakfast.
By the time you get to the car, the engine is destroyed.
By disabling remote start, the manufacturer is basically saving you from blowing up your engine. According to most owner's manuals (I checked the Chevy Silverado and Ford F-150 manuals specifically), this is listed under the "Conditions in which Remote Start will not work" section. They usually list:
- Hood is open.
- Hazard lights are on.
- Coolant temperature is too high.
- Oil pressure is low.
- The Check Engine Light is on.
Brand-Specific Quirks
While most cars follow the same rules, here are a few specific notes based on what I’ve seen with friends' cars.
Chevrolet / GMC / Cadillac
GM vehicles are strict about this. Even a "soft" code (a code that is pending but hasn't turned the light on fully yet) can sometimes disable remote start. If you have a Silverado or Sierra, checking the glow plugs (on diesel) or EVAP canister is the usual fix.
Ford
Fords typically disable the system, but they might also honk the horn at you if you try to remote start it with a CEL on. It’s like the truck is saying "No way."
Toyota / Lexus
Toyota is interesting because their remote start often shuts off when you open the door anyway (which is annoying). But yes, if the CEL is on, or even if the maintenance required light is on in some newer models, it might prevent the start.
Honda / Acura
Honda systems are very sensitive to battery voltage. Sometimes, if your car battery is just getting old and weak, it triggers a weird sensor code and disables remote start. If your battery is over 3 years old, get it tested.
When to Call a Pro
Look, I love DIY stuff. I think everyone should own a scanner. But there are times when you just need to take it to the shop.
If your scanner gives you a code regarding the Transmission or Timing Chain, stop. Don't try to fix that in your driveway unless you are really experienced. Also, if the Check Engine Light is flashing (blinking on and off), that means "Emergency." Do not remote start it. Do not drive it hard. Tow it to a shop.
A flashing light usually means active misfiring that is dumping raw fuel into the exhaust, which can melt your catalytic converter in minutes.
Summary
It is super frustrating when tech fails, especially in the winter when you just want a warm car. But remember:
Check Engine Light ON = Remote Start OFF.
Don't waste time replacing the battery in your key fob. Don't blame the starter. Scan the code, fix the sensor or tighten the gas cap, clear the code, and you'll be back in business.
Frequently Asked Questions
Q: Can I bypass the check engine light to use remote start?
A: Technically, no. The software is hard-coded into the car's body control module. You would need a custom "tune" or a third-party aftermarket remote starter installed to bypass the factory safety settings. It is generally not worth the risk.
Q: I cleared the code with a scanner but the light came back. Why?
A: Clearing the code with a scanner doesn't fix the car; it just deletes the error history. If the physical part (like a sensor or valve) is still broken, the computer will detect it again as soon as you drive and turn the light back on.
Q: Will remote start work if the tire pressure light is on?
A: Usually, yes. Most cars treat the Tire Pressure Monitoring System (TPMS) as a separate warning. It shouldn't affect your engine starting remotely. However, if the hood latch sensor is broken (telling the car the hood is open), that will prevent remote start.
Q: My check engine light is OFF but remote start still won't work. What now?
A: If there are no lights on the dash, check your key fob battery first. Then, check if your car has a "valet mode" switch that might have been bumped. Also, check your coolant levels; some cars won't remote start if coolant is dangerously low, even without a light on.
Q: Is it safe to drive with the check engine light on?
A: If the light is solid (not flashing) and the car feels like it is driving normally, it is usually safe to drive it to the mechanic or auto parts store. If the light is flashing, pull over and call a tow truck.