FIXED: remote start not working check engine light on

The Short Answer: Why It's Happening

Here is the deal: Your remote start is not broken. Your car is actually doing exactly what it was programmed to do. On almost every modern vehicle-whether it's a Chevy, Ford, Honda, or Toyota-the computer disables the remote start feature the second the Check Engine Light turns on.

Why? It is a safety precaution. When you remote start a car, you aren't sitting in the driver's seat to watch the gauges or listen for weird noises. If the engine has a serious problem (like low oil pressure or a severe misfire), running it without a driver present could destroy the engine in minutes. So, to protect your wallet and the car, the system just says "Nope" and refuses to fire up until you fix the problem.

Below, I’m going to walk you through exactly how to troubleshoot this, how to read the codes yourself, and the most common fixes so you can get your car warm (or cool) again before you get in.

Step 1: The "Gas Cap" Trick (Do This First)

Before you panic or call a mechanic, go outside and check your gas cap. Seriously.

This sounds too simple to be true but it's the culprit about 50% of the time. If you didn't tighten the cap enough the last time you filled up, or if the rubber seal on the cap is getting old and cracked, the car detects a "leak" in the fuel vapor system. This triggers the Check Engine Light.

What to do:

• Remove the gas cap.
• Put it back on and turn it until it clicks usually one or three times depending on your car.
• Drive the car for a few days.

It takes a few "drive cycles" (starting the car, driving, and turning it off) for the computer to re-check the system. If the light goes off on its own, your remote start will start working again immediately. If the light stays on, you're gonna need to dig a little deeper.

Step 2: Check the Hood Latch Switch

This is another one that drives people crazy because it sometimes doesn't even trigger a Check Engine Light, but it acts just like it. Most remote starters have a "Hood Pin" or a safety switch. This switch tells the car if the hood is open.

The logic is simple: If a mechanic is working under the hood, you don't want the engine to remote start and chop their fingers off with the fan belt. It’s a major safety liability.

If that sensor gets dirty, rusty, or bent, the car thinks the hood is open even when it's closed. If your dashboard says "Hood Open" but it is definitely shut, that is your problem right there. Clean the latch with some degreaser or WD-40 and see if that fixes it.

Step 3: Read the Engine Codes

If the gas cap is tight and the hood is closed, you have a legitimate engine code stored in the computer. You cannot guess what this is. You need to read the computer.

You have two options here and both are pretty easy.

Option A: Go to an Auto Parts Store

Places like AutoZone, O'Reilly's, or Advance Auto Parts will usually scan your check engine light for free. You just walk in and ask. They plug a little machine into a port under your steering wheel, and it gives them a code (like P0420 or P0301).

Option B: Buy a Cheap Scanner

Honestly, you should just own one of these. You can buy a basic OBDII scanner on Amazon for like $20. You plug it into the port under your dash (it looks like an old printer port), turn the key to the "On" position, and hit "Read."

Once you have the code, you can Google it. For example, search "Chevy Silverado P0442 remote start not working." This will tell you exactly what part is failing.

Common Codes That Kill Remote Start

While literally any check engine code will disable your remote start, there are a few that seem to pop up way more often than others. Here is what I usually see.

EVAP System Codes (P0440, P0442, P0455)

We talked about the gas cap earlier? That’s part of the EVAP system. This system traps gas fumes so they don't pollute the air. If there is a leak-either from the gas cap, a vent valve, or a charcoal canister-you'll get these codes. It won't hurt the way the car drives, but it will definitely kill your remote start.

Misfire Codes (P0300, P0301, etc.)

A misfire means one of your engine's cylinders isn't firing correctly. This is usually caused by bad spark plugs or ignition coils. If your engine feels a little "shaky" or rough at a stoplight, you probably have a misfire. The car disables remote start because running a misfiring engine can dump raw fuel into the exhaust, which ruins your catalytic converter.

Thermostat Issues (P0128)

This one is super annoying in the winter. P0128 means "Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)." Basically, your car isn't warming up as fast as the computer thinks it should. Since the whole point of remote start is to warm up the car, the system sees a conflict and shuts it down.

Oxygen Sensors (P0141, P0135)

Your O2 sensors live in your exhaust pipe and tell the computer how much fuel to give the engine. If a heater inside the sensor fails, the car can't manage fuel usage perfectly. According to sites like Wikipedia and general mechanic knowledge, these sensors are crucial for emissions, so when they fail, the system locks out non-essential features like your remote starter.

How to Reset the Light (And Get Remote Start Back)

Okay so you fixed the problem. Maybe you replaced the gas cap or swapped out a bad ignition coil. Now you need the light to go off so you can use your key fob again.

Method 1: The Scanner (Best Way)
If you bought that $20 scanner I mentioned, just plug it in and select "Erase Codes" or "Clear Codes." The light will turn off instantly. Try your remote start-it should work immediately.

Method 2: The Battery Disconnect (The Old School Way)
If you dont have a scanner, you can disconnect the negative (black) battery terminal on your car battery for about 15 minutes. This resets the car's computer.

Warning: This will also reset your radio presets and clock. On some newer cars, it might even make the car run a little funny for the first few miles while the computer "re-learns" your driving style. But, it usually clears the Check Engine Light.

Method 3: The "Wait and See"
If you fixed the problem (like tightening the gas cap), you can just drive. After about 3 to 10 trips where the car warms up and cools down, the computer will realize the problem is gone and turn the light off by itself.

Vehicle Specific Quirks

While most cars follow the rules I listed above, some brands have their own little weird issues.

Chevrolet / GMC / Cadillac

General Motors vehicles are strictly programmed regarding this. If you have a Chevy Silverado or Equinox, you will see a message on the dash saying "Remote Start Disabled" usually right after the CEL comes on. One weird quirk with GM is that sometimes stored "permanent codes" keep the remote start disabled even after you clear the light. You have to drive the car for a while to complete a "Drive Cycle" before it comes back.

Ford

Ford trucks (F-150s especially) are sensitive to the hood switch I mentioned earlier. Also, if your battery voltage is low, Ford systems will disable remote start to save power to ensure you can start the truck with the key. If you have no check engine light but remote start isn't working, check your actual car battery age.

Toyota / Honda

Japanese cars are very safety-focused. On many Toyotas, if you have a "TPMS" (Tire Pressure) light on, it sometimes won't interfere, but a "Maintenance Required" light might. However, the Check Engine Light is a 100% hard stop for their remote start systems.

Can I Bypass This?

I get asked this a lot. "Can I just override the computer and force it to start?"

The short answer is no, not with a factory remote starter. The software is hard-coded into the Body Control Module (BCM). You cannot change it without hacking the car's software, which is way more trouble than just fixing the O2 sensor.

If you have an aftermarket remote starter (like a Viper or Compustar), it might still work even with the engine light on. Aftermarket systems usually bypass the car’s internal logic and just send a "start" signal to the starter wire. However, I wouldn't recommend using it if you know your engine has a problem.

When to Call a Pro

Look, I love DIY stuff. But sometimes you have to know when to fold 'em.

• Flashing Light: If your Check Engine Light is flashing (blinking on and off) while the engine is running, do NOT remote start it. Do not even drive it. That means a severe misfire is happening that is actively damaging your engine. Tow it to a shop.
• Electrical Gremlins: If you scan the car and get 15 different codes for "Low Voltage" or "Lost Communication," you probably have a wiring issue or a bad ground. That is a nightmare to diagnose without professional tools.

Preventing This in the Future

The best way to keep your remote start working is just keeping up with basic maintenance.

Change your oil on time. If your spark plugs are due at 100,000 miles, change them at 100,000 miles. And please, be gentle with your gas cap. Don't crank it down like you're trying to seal a submarine hatch-just until it clicks.

Getting into a cold car in the morning is the worst. Hopefully, this guide helps you get that heater running before you even step out the door. Good luck fixing it!

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Frequently Asked Questions

Does disconnecting the battery fix the remote start?

Sort of. Disconnecting the battery resets the computer, which turns off the Check Engine Light temporarily. If the light is off, the remote start will work again. However, if you have a broken part (like a bad sensor), the light will come back on after you drive a few miles, and the remote start will stop working again.

My Check Engine Light is OFF, but remote start still doesn't work. Why?

If there is no light, check these three things:

1. Hood Latch: The car thinks the hood is open.
2. Key Fob Battery: Your remote might be dead.
3. Valet Mode: Some cars have a "Valet" switch that disables remote start. Check your manual to see if you accidentally toggled it.

How much does it cost to fix this?

It depends entirely on the code.

• Loose Gas Cap: Free.
• Purge Valve: $50 - $150.
• O2 Sensor: $100 - $300.
• Catalytic Converter: $1000+.

Most of the time, it's one of the cheaper fixes.

Is it safe to remote start the car if I clear the codes but don't fix the problem?

It’s usually safe for a short time, but not recommended. If the code was for something minor like an EVAP leak, it's fine. If the code was for low oil pressure or overheating, you could kill your engine by remote starting it. It's better to know what the code is before you ignore it.