P0294 OBD-II Trouble Code: Cylinder 12 Injector Circuit Low

P0294 code definition

P0294 is the universal OBD-II code for Cylinder 12 Injector Circuit Low.

What the P0294 code means

The fuel injector’s job is to deliver the right mixture of fuel and air to the engine. If this mixture is off balance, such as when there is a malfunction in the injector or its circuitry, the oxygen sensor sends a message to the PCM telling it that there is a lean mixture. Trouble code P0294 means that the number 12 cylinder in the firing order is experiencing either reduced or non-existent fuel delivery.

If the PCM gets the signal that there is a lean mixture in one of the cylinders, it automatically sends a message to the other cylinders telling them to deliver a richer fuel mixture. This series of events can impact multiple vehicle systems.

What causes the P0294 code?

Possible causes of this fault code may include:

• A bad fuel injector
• A clogged or dirty fuel injector
• A short or open in the fuel injector wiring or harness
• A malfunction in the PCM’s fuel injector driver
• A damaged or loose connector at the fuel injector

What are the symptoms of the P0294 code?

Likely signs of this fault include an illuminated Check Engine Light, reduced power, and decreased fuel economy. In addition, you may notice the engine running rough.

How does a mechanic diagnose the P0294 code?

The technician may take the following steps to diagnose this issue:

• Verify any set codes using a scanner, recording the freeze frame data and clearing the codes to see if they return

• Visually inspect the fuel injector connectors and wiring

• Observe the cylinder number 12 fuel injector while the engine is running to check for a faint clicking sound (to indicate normal function)

• Test the resistance and voltage of the fuel injector connector

• Testing the harness connector terminals

• Remove the fuel injector from the engine in order to visually observe the fuel spray

Common mistakes when diagnosing the P0294 code

A common error when trying to identify a cylinder 12 fuel injector problem is to replace the PCM without fully inspecting all other involved components. PCM failure is rare, so performing the full diagnostic procedure is vital to making an accurate diagnosis.

How serious is the P0294 code?

While a cylinder 12 fuel injector malfunction will not prevent the vehicle from running, the problem can affect the way the entire engine runs, compromising fuel economy and causing the engine to run rough. It’s wise to have this issue addressed by a professional as soon as possible.

What repairs can fix the P0294 code?

The following solutions may be required for this issue:

• Replacement of damaged electrical fuel injector connections
• Clearing the injector of clogs
• Replacement of the fuel injector

Most fuel injector problems are the result of corrosion in the connectors or wiring, a bad injector, or a clogged injector.

Additional comments for consideration regarding the P0294 code

There are fuel injector flushing kits available for home use, in case you want to try cleaning it out yourself, however the correct procedure must be followed. The fuel return line must be plugged so that the cleaner does not travel back to the fuel tank.

If you want to listen to the fuel injector to make sure it’s functioning (as evidenced by a clicking noise), hold a screwdriver tip to the injector with the handle at your ear. This helps to amplify the sound so that you can hear it more easily.

If all attempts at home repair fail, don’t hesitate to contact a trained technician. Engine problems can spiral out of control quickly if not properly repaired, so a P0294 code is something you want to attend to as soon as possible in order to prevent more serious damage.

Need help with a P0294 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.