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P2666 OBD-II Trouble Code: Fuel Shutoff Valve B Control Circuit Low

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P2666 code definition

The P2666 code identifies a problem with the fuel shutoff valve.

The P2666 code is often associated with the P2665 and P2667 trouble codes.

What the P2666 code means

P2666 is the OBD-II generic code for a problem with the fuel shutoff valve. Within the fuel shutoff valve circuitry, a circuit can be displayed as either “open” or “closed”. A circuit is “closed” when it is in its normal state and functioning properly. If the circuit is “open”, then there is a disconnection within the circuit. An “open” circuit is indicated by the P2666 code.

The location of the particular control circuit; “valve B” in this case, varies depending on the vehicle.

What causes the P2666 code?

The fuel shutoff valve code may have several causes:

What are the symptoms of the P2666 code?

Once the P2666 code is triggered, the Check Engine Light will illuminate on the vehicle’s dashboard. Depending on the particular vehicle, the engine may be unable to start. In some cases the engine will start, but will also suffer from insufficient fuel pressure to run correctly.

This problem will have similar symptoms to a problem with the fuel pump or other components within the fuel system.

How does a mechanic diagnose the P2666 code?

P2666 is diagnosed with an OBD-II code scanner that is capable of scanning the factory sensor readings. A qualified technician will perform the diagnosis using the machine. The first thing they will do is observe when exactly the code was first activated. They will then reset the code and test the vehicle.

If the vehicle is capable of starting, the mechanic will run the engine and perform a test drive while also viewing data from the engine live via the scanner. If the same code comes back, then an inspection of the wiring and electrical connections surrounding fuel shutoff valve B will take place. If no observable problems are noted, then the technician will perform a test of the circuit using a multimeter and an oscilloscope.

Common mistakes when diagnosing the P2666 code

Despite the accompanying trouble code, the fuel delivery problems associated with problems in the fuel shutoff valve are often misdiagnosed as a problem with the fuel pump or other components along the fuel delivery system. Before replacing or repairing any components, make sure the P2666 code has been cleared and has not returned. If the circuit is still “open”, then the P2666 code may be the cause of the fuel delivery problems.

How serious is the P2666 code?

The P2666 code can, in many cases, prevent the engine from starting. This is not true for all applications. In some instances, the engine will be able to run but will experience problems with fuel delivery. For these reasons, the P2666 code is relatively serious and should be diagnosed by a qualified technician as soon as possible.

In some cases, the P2666 code only appears intermittently. This could lead to a lengthier and more complicated diagnosis process, as the code should appear constantly. If the problem truly lies with the fuel shutoff valve, then the code should appear again immediately after being reset.

What repairs can fix the P2666 code?

The most common potential repairs to address the P2666 code are as follows:

  • Inspect the wiring and electrical connections in and around the fuel shutoff valve circuit for signs of corrosion or other problems.

  • Any wires or connectors showing signs of damage should be replaced or repaired as necessary.

  • If there are no more issues remaining with the wiring, then check the fuses that correspond to the fuel delivery system.

  • If the fuses are all in working order, then repairing the problem may require the fuel shutoff valve itself be replaced.

  • If there is a problem with the circuitry surrounding the fuel shutoff valve or if a short in the circuit has caused serious damage, the circuitry may have to be replaced. This may require reprogramming as well.

Additional comments for consideration regarding the P2666 code

Due to the fact that this is an electrical issue associated with the fuel delivery system, the appearance of the P2666 code is not definitive proof that the fuel shutoff valve has been deactivated. The code has to be reset so that a technician can observe whether or not the code appears again immediately. If the problem is intermittent, then it may not be properly diagnosed until the code appears again once the car is running.

Need help with a P2666 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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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