Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. Symptoms of a Bad or Failing Main Relay (Computer/Fuel System)

Symptoms of a Bad or Failing Main Relay (Computer/Fuel System)

main relay

The engine computer in your vehicle is a very vital piece of equipment. Without this part of your car running the right way, it will be nearly impossible for you to operate the vehicle as intended. In order for this part of the vehicle to operate correctly, it will need the power that the main relay supplies. The main relay helps to ensure that the engine computer gets the power that it needs to run and function as intended.

The main relay is usually located underneath the hood in the relay box. The high heat that this relay is exposed to can create a lot of damage over time. When the main relay begins to malfunction, you will have to find a way to address the issues in a hurry. Failure to act quickly in a situation like this can lead to a lot of instability.

The engine will not start

Most car owners take their engine for granted until there is an issue with it. If the engine will not crank, then you will need to get the main relay checked out. If the main relay is not supplying the engine computer with the power it needs, then the engine will not be able to crank and run the right way. Failing to get the main relay replaced will usually lead to the car being unusable.

The car can’t stay running for long periods of time

If the car cranks and then dies almost immediately after, then the main relay may be to blame. The only way to ensure that this problem stops is by taking the time to get the relay tested and replaced if needed. Having a car that cuts off all of the time can be very frustrating and dangerous in certain situations. Replacing the main relay is the only way to regain the consistency that your vehicle has lost.

The Check Engine Light is on

When the Check Engine Light on your car comes on, then you will need to take the time to have it looked at. The best way to find out why the light is on is by going in to a shop that has diagnostic equipment. They will be able to pinpoint what issues are causing the Check Engine Light to come.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...

Related questions

Q: Transmission lights no gears

Hello. Your BMW 745Li has a shutdown feature which helps to prevent additional damage to other components of the car when there is a problem with the engine and/or transmission. Using the information that you have provided, it sounds like...

Q: How to fix or replace damaged vapor hose

I would recommend going to the dealer to get a parts diagram to pinpoint the hose that is damaged. There is more than one hose on the fuel tank for the vapor recovery system and getting the correct one can...

Q: My engine light came on code shoed P0037 its a Lexus is300 is it just changing the o2 sensor?

P0037 is an oxygen sensor code referring to bank 1 sensor 2. This is the right hand side of the engine and the second sensor on that side. The code may be caused by the catalyst on that side or...