Air Pump Circuit Malfunction/ (AIR) System Bank 1
The secondary air injection (AIR) pump that helps reduce emissions on Bank 1 isn't working properly. Think of it like a bicycle pump that's supposed to inject extra air into the exhaust to burn off pollutants, but it's either not pumping or the ECU can't detect it working.
The ECU monitors voltage/current to the AIR pump relay and expects voltage presence when the pump is commanded on during cold start and fuel cutoff. It also monitors for proper pump operation feedback through current draw or sensor signals. A fault occurs when expected voltage or pump operation is absent.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| AIR pump voltage | 12V when commanded on | Below 10V or no voltage detected |
| Current draw | 3-8 amps during operation | No current or excessive current (>10A) |
Code P1420 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, P1420 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.