OBD-II code P2666 indicates that the engine control module (ECM) has detected a low voltage condition in the control circuit for fuel shutoff valve 'B'. This valve is typically used to stop fuel flow when the engine is turned off, and a circuit low fault may prevent the valve from operating correctly, potentially causing starting or stalling issues.
The solenoid or valve itself may have an internal short or high resistance, causing the circuit to read low voltage. This is the most common cause.
The control circuit wire may be chafed or pinched, causing a direct path to ground and pulling the voltage low.
Corroded, broken, or loose wiring/connectors can increase resistance, leading to a voltage drop that the ECM interprets as a low signal.
Corrosion, bent pins, or a loose connector at the valve can cause intermittent or high-resistance contact, resulting in low voltage readings.
In rare cases, the ECM may have an internal driver failure that cannot supply sufficient voltage to the circuit. This should only be considered after all other possibilities are ruled out.
It means the engine control module has detected a low voltage condition in the circuit that controls fuel shutoff valve 'B'. This valve is used to stop fuel flow when the engine is turned off, and a circuit problem can cause starting or running issues.
It is not recommended. The vehicle may stall unexpectedly or fail to start, which could be dangerous in traffic. You should diagnose and repair the issue promptly.
No, a faulty PCM is rarely the cause. The problem is usually a bad fuel shutoff valve, wiring issue, or poor connection. Replacing the PCM should only be considered after all other possibilities have been thoroughly tested and eliminated.
The most likely causes are a defective fuel shutoff valve itself, a short to ground in the wiring, or a poor electrical connection at the valve. Start diagnosis by inspecting the valve and its circuit.