[Metaldog]

Potential causes for the 'circuit high' codes include:
Faulty electrical harness from the PCM to the injector. Faulty electrical connector on the fuel injector. Internally shorted fuel injector causing a high-voltage draw. Plugged or dirty fuel injector.

Diagnosis and Repair Procedure:
It's been my experience over the years, that the problem is typically a corroded or loose fuel injector connector, or a faulty fuel injector. A loose connector causes excessive resistance thereby increasing the voltage necessary for operation. The wiring harness to the powertrain control module (PCM) is not easily accessible, and left undisturbed is seldom faulty. The fuel injector, on the other hand, is susceptible to a variety of problems. The number one problem is fuel with anhydrous ethanol content. This fuel additive reduces the oil base fuel consumption. The water vapor produced with E10 anhydrous ethanol has an adverse effect on the fuel injectors. They rely on fuel for lubrication. Water vapor reduces the friction reducing attributes of gasoline and causes premature wear in the injector. Small engine manufacturers do not endorse the use of ethanol based fuels as they significantly reduce the service life of a small engine.

• Inspect the electrical connector on the fuel injector. Look for bent or pushed out pins.

• Install some dielectric grease and push the electrical connector on the fuel injector. Make sure it is a tight fit and the metal spring retaining clip is in place.

• Start the engine. Place a long screwdriver handle to your ear and the tip on the fuel injector. A clicking sound indicates a working injector. No sound is the opposite Disconnect the fuel injector.

• With an ohmmeter, check the resistance between the two male terminal blades. A good injector will have 0.5 to 2.0 ohms. More or less ohms indicates an injector with an internal short.

• If the resistance is correct and the injector could be heard operating, the next step is to attempt to clean the injector. If cleaning fails to restore the injector to normal operating parameters, the only alternative is to replace the injector.

• Purchase a 'direct injection cleaner kit consisting of a can of cleaner and a injection hose. Pull the fuel pump fuse and start the engine. Allow it to run until it stalls.

• Remove the schrader valve from the fuel pressure test port on the fuel rail. Install the hose on the test port.

• Pinch off the fuel return line directly behind the fuel pressure regulator using a needle nose vise grips.

• Open the bottle of cleaner to build pressure in the fuel rail.

• Start the engine and allow it to run on the bottle of fuel injection cleaner until it stalls.

• Turn off the key and remove the cleaner hose from the test port. Install the schrader valve, remove the vise grips from the return line and install the fuel pump fuse.

• Use a common code scanner to erase the trouble codes. Start the engine. If the code returns, replace the injector.

Article by Don Bowman, ASE Certified Automotive Tech

Read more at: http://www.obd-codes.com/p0271
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[Metaldog]

Without diagnosing it in person, The problem could be one or multiple cause(s). Since faulty wiring is, in my experience, rarely the cause, I'm almost willing to bet that your injectors have become clogged and need replaced.

The best way to diagnose them is to, first, check the OHM resistance. Secondly, (if OHM range is good) to do a fuel pressure test, which involves a specialized machine designed for testing injectors. That said, if you had a trouble code on only one injector, there is another method for testing fuel injectors that doesn't require a machine, and can be done in the engine itself.

However, since you have codes on all of them, I'm inclined to thinks it's the injectors. It could still be an electrical issue, though. So, your idea of seeking an auto electrician is a good judgement call. Hopefully, he/you can figure it out, and resolve the issue.

Good luck to you!