Honda Accord Won’t Start When Hot Outside [Explained!]

Honda Accord is one of the most popular cars for its sleek looks and premium touch. However, there have been recent cases reported where Accord won’t start in hot weather conditions. We understand if you are facing the same issue with your Honda Accord.

So, why does your honda accord won’t start when hot outside?

There could be several reasons why hot weather could cause your Accord to not start. Firstly, it could be your fuel that’s evaporating faster. Or, it could be your battery. It could also be the engine oils that you’re using causing this commotion. Or, it could very well be your coolant levels.

That’s not all. You need much more information to fix this issue. In this article, we’ve thoroughly discussed all these issues and mentioned ways that you can solve them.

So, what’s stopping you? Let’s get down to fixing it, shall we?

4 Reasons Why Your Accord Won’t Start in Hot Weather [Solved!]

There have been many cases like 2003 honda accord intermittent starting problems. Also, people have reported 2004 honda accord intermittent no start. As explained earlier, there are 4 major reasons why your Honda Accord is facing this issue. 

However, there is much more information that you’ll be needing to spot and fix these problems. This section covers all these probable reasons for engine failure and how to fix them!

Reason 1: Fuel Vapor-Lock

You wouldn’t see traditional automobile enthusiasts facing this problem of vapor lock. It’s an issue that only exists in the modern era. 

When there is boiling fuel in the carburetor or sometimes fuel line, vapor lock forms. Back pressure generated from vaporized gasoline inside the fuel system stops fuel from reaching your engine.

It usually happens after a car’s been sitting in direct heat for a long. It can also happen when you just switched off your car and tried turning it on. 

And in this case, your Honda Accord also comes with fuel injectors.

Install a transparent line between the fuel pump and the carburetor intake. This will help you to confirm if it’s a vapor lock. You will be able to watch the pipe filled with fuel without any air bubbles.

In hot weather, the temperature of the gas line might exceed 120 degrees. Modern fuel mixes, however, may boil at temperatures like 100 degrees.

If you have this issue, air bubbles will form when you crank your engine after idling. People encounter this same issue when their honda civic no start when hot.


Installing an electronic carburetor or attaching a plastic carb spacer are two options for resolving vapor-lock. We recommend you use an Aeromotive in-tank fuel pump along with a return system.

It’s a cooling-down system for which surplus gasoline is transferred to the fuel tank. In contrast, other systems keep gas in the pipeline and enable it to absorb additional heat.

After you’ve installed the kit, there’s only one thing that you need to do.  That is to replace the pressure regulator spring. And that will solve the issue for your Honda Accord.

Reason 2: Drained Battery 

You usually picture a dead battery in chilly winter weather when you consider battery troubles. Summer heat, on the contrary, can be more detrimental to your Accord’s battery than cold weathering conditions. 

Summer’s scorching heat can deplete your battery’s startup power and shorten its life. So, If your Accord is facing start-up issues in hot weather, it could be your battery. 

It’s possible that it’s related to your battery, as extreme temperatures may quickly reduce battery life. This is due to the fact that batteries contain liquid that can vaporize in hot weather.

Summer temperatures may cause liquid to vaporize out of the electrolyte of a lead-acid battery. This could obstruct the battery’s current flow as well. In a similar case, your Accord will not start after idling in the summer heat.

When these liquid levels fall excessively low, the battery’s interior plates may be compromised as well. This will result in lower voltage output.

You can use a multimeter to check if it’s actually your battery not providing enough power. Follow the following steps to check your battery with a multimeter:

  • After your car has been parked in heat, examine your battery after it has been sitting for some time. You’ll receive your car’Accord’s “resting voltage”. This will provide you with a solid idea of its general condition.
  • Now, locate your Accord’s battery, which is normally placed on one side of the engine.
  • Check to see if you can get to your battery connections.
  • Sometimes batteries include plastic covers that may simply be slid off. but others may need the removal of bolts.
  • Then, you have to set your multimeter to 20 DC volts on the dial.
  • Red and black probes are included with most multimeters. Connect the positive (+) connector of your battery to the red probe, and the negative (-) connector to the black probe.

This way you can check if your battery is actually the problem or not. The reading should exceed 12.6 volts if the battery’s A-okay.


Check your battery for symptoms of corrosion regularly. You can use a copper brush to remove any corrosion.  A scouring pad would also do the trick! 

It’s important to check each cell’s water level. If it’s low, top it up with water. Make sure to use distilled water. If the battery is old, it’s better to change it than to repair it.

Reason 3: Insufficient Coolant

Engine coolant is kept inside the radiator toward the front of your Accord. It’s circulated in between the engine and radiator to keep it cool as per requirement. The engine’s high temperature is passed to the coolant, which increases in volume in high temperatures.

The recovery tank between two components tackles this mass pressure generated by the expansion. The temperature would also spike in the hoses that carry the coolant. The overflow caused by the increased coolant is stored in this tank.

As the recovery tank fills up, it leaks coolant over the ground. You’d experience this during the summertime when your coolant battles with the constant heat. The strains of a hefty air conditioner also add up to it.

The coolant turns to its original volume when cooled down, except for any overflowing coolant. Coolant loss can occur if coolant spills occur often. Examine level indicators on the recovery tank to determine your Accord’s coolant level.

The coolant level should be visible through the recovery tank’s transparent plastic exterior. 


Refill coolant up to a level between the “Low” and “Full” if it is under “Low”. Filling the tank to the brim will not harm your Accord. 

However, the excess coolant will simply leak out when the tank becomes overheated.

Reason 4: Vaporized Engine Oil

In Layman’s terms, oil is affected by temperature. Temperatures alter the viscosity of an oil, which might affect the performance of your Accord’s engine.

Previously, motorists adapted for natural temperature fluctuations by using various types of oil at different seasons of the year. Lighter oils in the winter and thicker oils in the summer. 

This was required at the time to keep the engine lubricated properly. Exceptional cold temperatures could really cause the fluid to crystallize. This results in poor oil flow all through the engine and insufficient lubrication. 

Contrarily, using synthetic oil with a viscosity that is too low won’t cut it. It will not provide enough smoothness between the metal components, especially in extreme heat.

Due to the use of Viscosity Index Improvers, multi-viscosity oils have rendered seasonal engine oils obsolete. VIIs adjust for the wide temperature range to which a car engine may be subjected. 


Use thicker engine oil during extreme heat. Or you can go for multi-viscosity engine oils.

5W-20 is a popular multi-viscosity oil. The “W” indicates  “winter” and the grade denotes a lower absorption rate. The ingredients in these oils allow the oil to effectively lubricate the engine when it first starts up.

Lubricant deterioration can occur at both ends of the temperature range. Here we are mentioning two great multi-viscosity oils just for you!

Hopefully, you’ll love them!

This was all about our insights on why your Honda Accord is acting this way. People face similar issues where honda crv won’t start when hot outside. We hope that these solutions will work out for you during high temperatures. 


Why does your Honda Accord crank but not start? 

Commonly, if your Honda Accord isn’t starting it’s because your engine isn’t getting enough fuel. This can happen due to several reasons. You could have a defective fuel injector or a jammed fuel filter. You could have worn spark plugs as well. All these can obstruct the flow of fuel in your engine.

Why won’t your Honda Accord start if the battery is okay? 

Mostly when the car won’t start at all, the problem is a dead battery. But, if your Accord’s battery isn’t that old, it could be a connection issue or corrosion. Use a cloth to clean your battery’s terminals. Also, try cleaning the cable connectors. Otherwise, it could be your starter or alternator.

How to know if it’s your battery or your alternator? 

In general, cases, if your battery won’t hold a charge, the usual suspect is the alternator. A faulty alternator will cause your car to die when you hit the accelerator. However, if your battery is all charged but your car won’t start, it’s the battery. Alternator problems are much harder to solve.

End Note

Hopefully, now you know why your honda accord won’t start when hot outside. We hope that you will be able to identify the specific reason and solve it! 

We strongly recommend you use multi-viscosity engine oil for your engine. It’s much better than the old school “Thick-Thin” method that’s obsolete these days,

We will see you in another article very soon. Till then, Happy Driving!

Rob Dahm

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