P0279 OBD-II Trouble Code: Cylinder 7 Injector Circuit Low

P0279 code definition

Code P0279 is stored by the PCM when it experiences a low-voltage situation that involves the fuel injector for the number seven cylinder.

What the P0279 code means

Basically, this code means that one of your vehicle’s fuel injectors is failing, which could be happening for a number of reasons. Every make and model has a voltage spectrum that is considered acceptable by the manufacturer’s predetermined standards. Voltage variations that exceed 10% of this acceptable range will cause the code to be stored. Usually, a Check Engine light comes on too.

What causes the P0279 code?

Many things could cause a voltage issue with the number seven fuel injector. The most common reason would be that the wiring has been damaged by wildlife. Squirrels and other creatures can sense the warmth from your engine after it’s been in use and will climb up under your hood and snuggle up to it. Unfortunately, many won’t be satisfied with the extra warmth and will actually chew through wires.

Other causes include:

• A clogged fuel injector
• A defective fuel injector
• Loose connector faces
• Loose electrical wiring
• Corroded electrical features
• A bad fuel injector driver within the PCM

What are the symptoms of the P0279 code?

When a fuel injector isn’t working properly, you should expect a lack of power coming from the engine. It will most likely run a lot rougher too. Your fuel economy should take a hit as well. On most vehicles, you’ll also see the Check Engine light come on, though it might take a few failed cycles before this happens.

How does a mechanic diagnose the P0279 code?

A qualified mechanic will begin by using a scanner to diagnose what codes are affecting your vehicle and then use a noid lamp, ohmmeter and the service manual to get a better idea of the issue behind P0279, specifically. Then they’ll move onto doing a visual examination of all connectors and wires. Usually, this is all that is necessary, but in some cases, the fuses may need to be checked on too. After each inspection, the code should be cleared and the system retested before moving on.

Common mistakes when diagnosing the P0279 code

PCM failure could be a reason for the P0279 code, but it’s incredibly unlikely. Before the PCM is ever replaced, every other possibility should be exhausted. A lot of times, it’s just open or shorted circuits inhibiting the defective fuel injectors or fuel injection system that make it seem as though the PCM isn’t working correctly.

How serious is the P0279 code?

The P0279 is not one you want to be driving around with. Having it fixed should definitely be an immediate priority. Any time one of your fuel injectors isn’t working correctly, you run the risk of all kinds of other problems occurring – some of which could be very expensive to repair. Fuel injectors are central to your vehicle’s operation, so if one doesn’t work correctly, it causes a ripple effect. The PCM will even change up how your engine works to accommodate the missing signals from fuel injector number seven.

What repairs can fix the P0279 code?

To repair the problems related to P0279 code, your mechanic will likely do one of the following:

• Clean a dirty injector
• Replace a bad injector
  
• Replace or tighten the injector’s electrical connector

The majority of the time, your mechanic will do the last one on this list. Corroded or simply loose connectors keep the injector from receiving sufficient voltage.

Additional comments for consideration regarding the P0279 code

It’s pretty hard to misdiagnose this one, but some have accidentally blamed the PCM because they didn’t inspect the fuel injectors well enough. This is a costly mistake.

Need help with a P0279 code?

YourMechanic has certified mobile mechanics who will visit you at your home or office to assess your vehicle and perform any necessary repairs. You can fill out an online form or give us a call at 1-800-701-6230 to schedule your appointment with one of our service advisors and receive a free quote.