Fault code P0278 – cylinder 6 contribution balance fault

Fault code P0278 is called “Cylinder 6 Contribution Balance Fault” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0278

Stored code P0278 means that the Powertrain Control Module (PCM) has detected an incorrect balance distribution for a particular engine cylinder. In this case, the problem affected cylinder #6.

Fault code P0278 – cylinder 6 contribution balance fault

The Powertrain Control Module (PCM) monitors the power output of each cylinder. By comparing the acceleration or increase in crankshaft speed during the working stroke. When one or more cylinders produce less power than the other cylinders, fault code P0278 is set.

Using CKP sensors, the ECM control module can detect small changes in engine speed. That is, the acceleration of each stroke, and can determine how much each cylinder affects the engine, that is, the balance between each cylinder.

If one or more cylinders do not provide this impulse to the crankshaft, the PCM controller determines this to be a malfunction. It writes a Diagnostic Trouble Code (DTC) into memory and turns on the Malfunction Indicator Light (MIL).

Essentially, this code indicates that cylinder #6 is experiencing a fuel related problem when the fuel mixture is ignited.

Symptoms of vehicle malfunctions

The main signal that an error P0278 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
  2. Floating revolutions, vehicle engine may be unstable.
  3. Increased fuel consumption.
  4. The engine may stall or fail to start.
  5. Jerking/missing ignition at idle or under load.
  6. Bad acceleration.

The severity of error P0278 is above average, caution should be exercised. Because the vehicle may have serious problems potentially affecting safety.

Factors that can cause this error code

The error code P0278 can mean that one or more of the following problems have occurred:

  • Opened or short-circuited injector wires.
  • Clogged fuel injector.
  • Complete failure of injector.
  • Wiring harness is intermittently shorted to components under the hood.
  • Loose or corroded connector.
  • Sometimes faulty PCM module is the cause.

How to fix or reset OBD-2 code P0278

Some suggested steps for troubleshooting and fix the error code P0278:

  1. Read all stored data and error codes with an OBD-II scanner.
  2. Clear the error codes from the computer memory.
  3. Test-drive the vehicle to see if error P0278 appears again.
  4. Visually inspect the fuel injectors and associated wires and connectors for damage.
  5. Check the operation of the fuel injectors.
  6. If necessary, check the operation of the fuel injectors on a special test bench.
  7. Test the power control module (PCM).

Diagnose and repair of problems

Due to the complexity of the system and the cost and availability of tools, you may be limited in your ability to diagnose code P0278. Nevertheless, there are some actions you can take to eliminate this error.

Check the battery voltage (12 V) on the injector connector wire. If there is no voltage, check for continuity to the ground using a test lamp. Connected to the plus side of the battery. If it lights up, there is a short to the ground in the voltage supply circuit.

Correct the short in the voltage supply circuit and restore proper battery voltage. Remember to check the fuse and replace it if necessary.

One injector may short out the battery voltage to all injectors.

If battery voltage is being supplied to the injector wiring harness, the next step is to turn on the light to check that the injector driver is working. Install the injector light in the injector wiring harness instead of the fuel injector. This will flash quickly when the injector driver is operating.

Check the resistance on the fuel injector if you have resistance specifications. If the resistance is above or below the rating, replace the fuel injector. If the injector passes the test, the problem is probably unstable wiring.

Remember that a fuel injector can work fine when cold, but be faulty when hot, or vice versa.

Check the wiring harness

Check the wiring harness for chafing, and the connector for loose contacts or a broken lock. If necessary, repair and check if error P0278 returns.

Disconnect the PCM connector and connect to the fuel injector driver circuit. Any resistance indicates a problem. Endless resistance indicates a break in the circuit. Locate and repair, then try again.

If you can’t find any problems with the harness, but the fuel injector driver isn’t working, check the PCM power and ground. If they are OK, the PCM itself may be faulty.

If the electrical part is OK, the injector itself is probably clogged or contaminated. Try cleaning it, the flushing kit is inexpensive and will also help the other injectors work better. If flushing does not solve the problem, the injector must be replaced.

On which vehicles does this problem occur most frequently

Fault code P0278 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi
  • DAF
  • Ford

Fault code P0278 can sometimes be found with other errors. The most common are the following: P0263, P0266, P0269, P0272, P0275, P0281, P0284, P0287, P0290, P0293, P0296.

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