Split Air #1 Circuit Malfunction
Your engine's secondary air injection system (which pumps fresh air into the exhaust to reduce emissions) has a wiring or component problem in its primary circuit. It's like a check valve in your plumbing that's either stuck or disconnected, preventing air from flowing where it needs to go.
The ECM monitors voltage signals from the secondary air injection pump relay circuit and solenoid valve. It detects open circuits, short circuits, or resistance values outside normal operating parameters when the system should be active during cold start and warm-up phases.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Circuit Voltage | 12V when activated, 0V when deactivated | Stuck high/low, no voltage change, or excessive resistance |
| Relay Continuity | Ohm reading 70-90 ohms | Open circuit (infinite ohms) or short (near 0 ohms) |
Code P1423 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, P1423 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.