SAI System Monitor Circuit Low Input
The Secondary Air Injection (SAI) system pump isn't sending the expected electrical signal to the engine computer. Think of it like a weak handshake—the ECU expects a firm grip but is getting barely any signal back.
The ECU monitors the voltage signal from the SAI pump relay or solenoid circuit. When the SAI system activates, the ECU expects to see a voltage rise within a specific range. A low input voltage indicates the pump may not be operating or the circuit has high resistance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SAI Circuit Voltage | 9-14 volts (when activated) | Below 5 volts or open circuit |
| Current Draw | 2-8 amps | Below threshold or no draw detected |
Code P1418 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, P1418 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.