Recirculation Override Circuit Malfunction
Your engine's exhaust recirculation system has a control circuit that isn't working properly, like a valve that's stuck and won't respond to commands. The engine computer can't properly regulate exhaust gas flow back into the combustion chamber.
The ECM monitors the EGR (Exhaust Gas Recirculation) recirculation override solenoid circuit for proper voltage and current draw. It checks if the circuit can achieve expected control signals and solenoid actuation within normal parameters. A malfunction occurs when the circuit fails to respond to command signals or shows abnormal electrical resistance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Solenoid Control Voltage | 12V when activated, 0V when deactivated | Voltage stays below 10V or above 14V consistently |
| Circuit Resistance | 4-10 ohms | Open circuit (infinite) or shorted (under 1 ohm) |
Code P1663 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1663 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.