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P0266 OBD-II Trouble Code: Cylinder 2 Contribution/Balance Fault

Check Engine Light

P0266 code definition

Cylinder 2 Contribution/Balance Fault

What the P0266 code means

This diagnostic trouble code indicates that the powertrain control module has detected that the reference voltage from the fuel injector on cylinder 2 has fallen out of the range of acceptance set by the vehicle manufacturer.

What are the causes of the P0266 code?

  • Damaged wiring or connectors associated with the fuel injector circuit on the number 2 cylinder may be present.

  • A faulty or restricted fuel injector on the number 2 cylinder may exist.

  • The powertrain control module could be malfunctioning.

What are the symptoms of the P0266 code?

Symptoms of this trouble code that the driver may experience would include:

How does a mechanic diagnose the P0266 code?

  • A mechanic may begin diagnosing this trouble code by removing any engine covers that exist to gain access to the fuel injectors.

  • Once the fuel injectors are visible, the mechanic would inspect the wiring and connectors for damages that may have been caused by mice or other small animals that could have nested under the engine cover.

  • Next, the mechanic would test the fuel injector on the number 2 cylinder for proper function using the manufacturer’s suggested procedure.

  • If the cause of the issue has still not been revealed after these two tests have been performed, the mechanic would use a high tech scan tool to test the powertrain control module to ensure that it is working correctly.

After all tests have been performed and the mechanic has come up with a diagnosis, he/she would relay the information over to the customer to make an informed repair decision.

Common mistakes when diagnosing the P0266 code

A common mistake that could be made when diagnosing this trouble code would be to replace the fuel injector on the number 2 cylinder when it is actually the wiring or connector that is faulty. It is very important to check all possible causes of a problem before making a repair decision.

How serious is the P0266 code?

This code would be considered serious because the engine will not run properly with the cylinder 2 injector not functioning as it should. This issue would be worse on 4 cylinder and 6 cylinder engines as opposed to 8 cylinder engines due to the fact that the extra cylinders can make up for the imbalance that the malfunctioning injector on cylinder 2 would cause. A code such as this should be diagnosed and repaired as soon as possible because continuous driving with a misfire condition can cause damage to the engine.

What repairs can fix the P0266 code?

  • Repairing or replacing the wiring or connector that is associated with the fuel injector on the number 2 cylinder

  • Replacing the fuel injector on the number 2 cylinder.

  • Running a good fuel system cleaning through your engine to clear any restrictions the fuel injector on the number 2 cylinder may have.

  • Replacing the powertrain control module

Additional comments regarding the P0266 code

This code will likely be associated with a P0302 code for a cylinder 2 misfire. While the mechanic is inspecting the fuel injector circuitry, it would be a good idea to have him/her check the wiring on the ignition coil or spark plug wire to be sure that the ignition going to the number 2 cylinder is working properly.

Need help with a P0266 code?

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