P0403 indicates that the engine control module has detected an open circuit in the EGR valve control circuit. This prevents the EGR valve from receiving the commanded signal, so exhaust gas recirculation cannot be modulated.
The internal coil of the EGR valve solenoid can open, creating an open circuit that the PCM detects.
Frayed wires, broken pins, or a disconnected connector can interrupt the control signal.
A fuse that protects the EGR valve driver may have opened, removing power to the solenoid.
A poor ground connection can appear as an open circuit to the control module.
An internal sensor failure can cause the PCM to interpret the circuit as open.
Rarely, the driver transistor inside the control module fails, but this is a low‑probability cause.
Yes. An open coil inside the EGR valve solenoid is the most common cause of this code.
The vehicle can usually be driven, but emissions will be higher, fuel economy may suffer, and the engine could run rough or overheat under load.
No. Clearing the code only resets the light; the underlying open circuit will cause the code to return.
PCM failure is extremely rare for this code. Most often the fault is the valve solenoid, wiring, fuse, or ground. Replace the PCM only after all other circuit tests have been exhausted and the driver output is confirmed faulty.