Cylinder 4 Injector Circuit High
The engine computer detected that cylinder 4's fuel injector is receiving too much electrical voltage, like a light switch stuck in the on position. This prevents the injector from opening and closing properly, disrupting fuel delivery to that cylinder.
The ECM monitors the injector control circuit voltage and pulse duration during fuel injection events. It expects the injector to switch between ground and battery voltage within specific timing windows. A high voltage condition indicates the circuit is not properly grounding or the injector solenoid coil resistance is out of range.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Injector Control Voltage | 0-5V switching at 10-15 kHz | Sustained high voltage above 12V or insufficient voltage drop |
| Injector Pulse Duration | 1-15 milliseconds at idle | Abnormal pulse width or no voltage drop detected |
Code P0272 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, P0272 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.