What Causes Low Voltage to Fuel Injectors? We Explain

If your fuel injectors get low voltage, this may happen because of bad fuel injectors, problems with the wiring harness, or issues with the ECU or injectors control module. Also, there may be problems with the overall voltage in your vehicle. There are many things you will need to check and some of them are really hard to inspect on your own.

Electrical power supply problems highlights

• DIY repairs:possible (sometimes)
• Tools needed:electrical tools,basiccar repair tools
• Commonreasons:battery or alternator problems, wiring issues, power distribution problems
• Time to repair:2 - 5 hours
• Price for parts:$10 - $350
• Can you drive?In most cases, no
• Alternative solutions:jumping, roadside assistance

Symptoms of low voltage to fuel injectors

Unfortunately, this problem is not that easy to locate and understand. Very often, the low voltage on your fuel injectors problem may be hiding under very unclear symptoms that can mean anything. That's why, this is never the obvious thing to check and it often remains unnoticed. I should also tell you that locating the low voltage is not that easy, especially if you don't have any prior experience.

But you may deduct the problem just by checking other, more obvious, issues and also by analyzing the possible symptoms. They may be different, but they always combine something of the following:

• Bad start. Your car may crank for a long time before it starts or it can refuse to start at all.
• Uneven idling. When your RPM needle on the tachometer jumps like crazy when idling, this is one of the clear symptoms.
• Loss of power. The car with low voltage on the fuel injectors will not be fast and furious. It will be weak and stalling at every other corner.
• Stalling. If your car suddenly stalls when you stop at the red traffic light, it also may mean that injectors don't supply the engine with the needed amount of fuel.
• Check engine light. It may be triggered by a bunch of codes. There are codes for injector voltage but this problem will also trigger other codes like misfiring cylinders, exhaust problems, etc.

Now, if the voltage on your injectors is not high enough, it doesn't mean that your car will experience all these symptoms altogether. In most cases, you will have a combination of two or three symptoms. Or even just one symptom if the voltage is just slightly lower.

Also, you need to know that the voltage on your injectors is pulsing all the time, so measuring it with a simple multimeter may be challenging. If it shows 12.5 Volts while the battery shows 14.2 Volts, it doesn't mean that there is a problem. So, measuring the voltage on your injectors is not as easy as you may think.

Common reasons for low voltage to car injectors

Instead of trying to check the voltage with a multimeter (which is close to impossible), you may want to check the reasons that may cause this problem. Sometimes, in the process of inspection, you will find out that the problem is not in the voltage but in some other thing like a fuel pump problem or a clogged injector.

So, let's go through the most common reasons that may trigger the low-voltage problem with your injectors and that you may want to check, in the first place.

1) Injectors are faulty

If the injector is broken, it may show the symptoms of low voltage or something like that. It may even throw the code that will tell you about low voltage problems. But actually, this may be triggered by the problems in the injector itself.

Fuel injectors are not eternal. While OEM injectors can live quite long (and still not as long as the engine), some aftermarket parts have only 20-30 thousand miles lifespan. So, they will need to be replaced or cleaned, from time to time.

2) Injector wiring is bad

It's not uncommon for injectors to have problems with wiring and connections. First of all, this happens after the injectors are installed incorrectly. For example, the clamp may not be clicked properly and it works intermittently. Or the wires are damaged during installation.

Also, the wiring may be bad because of its age, water damage, heat damage, etc. This means you will need to pay attention to the wiring which is not that easy. Locating such a problem may take hours even if a professional mechanic inspects the car.

3) Problems with the battery or alternator

Whenever there's a problem with voltage at any unit of your car, it's worth checking the 12V battery and the alternator. Measuring voltage at these units is easy and you may do this in different conditions - when the car is off, when the starter motor is cranking the engine, when the car is on when the RPMs are high.

You need to get about 12.5 V when the vehicle is off and up to 14.7 V when the car is running. If something is wrong with the battery and/or with the charging system, you need to pay attention to these issues.

4) ECU problems

It's not that common for injectors to have problems with voltage because of the ECU. But if nothing else works, you may try checking this reason. The ECU is the unit that controls the work of the injectors. It sends the needed voltage to the injectors.

If the ECU is faulty or there is a glitch, the voltage to your injectors may be changed. You may try resetting the ECU by disconnecting the battery for several minutes. If this doesn't help, the ECU will need to be inspected by a professional mechanic.

5) Injector control module

More and more cars now have another electronic module to control injectors. It's governed by the ECU but it has more functions and its initial task is to operate the injectors as effectively as possible.

Checking this module is not easy unless you have special tools and some experience. So, you should rely on a professional if you suspect this module is faulty.

Any DIY methods to solve the problem?

Well, the DIY repair and inspection methods, in this case, depend on the level of expertise you have and the tools you possess to help you inspect the vehicle.

For an average driver, it's possible to check such things:

• the voltage on your battery terminals in different conditions;
• voltage on the alternator terminals when the car is working;
• error codes in the ECU with the help of the OBD2 scanner;
• visual inspection of the wiring that powers the fuel injectors.

I believe this is it - for any more complicated inspections, you should go to a good shop or to the dealership.

Can you drive with low voltage to the injectors?

It depends on how bad the problem is. If your car stalls at every corner and it takes several minutes to start, I wouldn't drive such a vehicle. This is just not safe and you may get into a road accident after losing control over your vehicle.

But if the symptoms are mild and the car works a little harshly with a check engine light on, you may drive on your own directly to the shop or dealership. I still don't recommend ignoring the problem because it may develop badly at any minute.

Driving your vehicle with low voltage to the injectors is not that safe even if the symptoms are not serious right now. This problem may get worse unexpectedly and you may find the car stalled when you are driving at a decent speed.

How much is it to repair the improper voltage problems?

When the voltage to your injectors is incorrect, it's more than possible that the car will be impossible to drive at all. So, you have no choice but to repair the problem. Where should you go and how much will it cost?

If the vehicle is still under warranty, you should start with the dealership. They will inspect the vehicle, check if there is a service bulletin or a recall from the manufacturer, and will tell you what to do next.

If you go to the independent shop, the inspection and repair will most likely be cheaper. But your warranty may be voided.

The repair may cost anywhere between $100 for some minor electric problems and several thousand dollars for serious issues with the ECU or wiring harness.

Final thoughts

If you suspect that the injectors in your car don't get the proper voltage, it's now the right time to go to the shop. Driving with such a problem is not safe and things may go fatally bad at any moment. I strongly recommend going to the dealership and having your vehicle inspected there. It may be one of the common problems with your model and the dealership mechanics will know about that.

Also, to repair the issue, you should only get OEM parts, unless the problem is in the 12V battery. Aftermarket wiring, control units, connectors and clamps, or injectors are just not durable and are not usually worth their money.

Any questions? Ask them in the comments below!