Cylinder #6 High To Low Side Short
The fuel injector circuit for cylinder 6 has a short between its high and low voltage sides, like a wire accidentally touching where it shouldn't. The engine's computer detected abnormal electrical resistance in the injector driver circuit.
The ECM monitors the fuel injector circuit voltage and current patterns during switching cycles. It detects when the high-side driver shorts to ground or the low-side pathway, creating an abnormal resistance condition below expected thresholds.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Injector Circuit Resistance | 12-16 ohms (coil resistance) | Below 5 ohms or open circuit detected |
| Peak Injector Current | 0.8-1.2 amps during pulse | Excessive current spike or dropout |
Code P1271 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, P1271 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.