Cylinder #8 High To Low Side Short
The injector circuit for cylinder #8 is shorted, meaning the electrical signal is dropping unexpectedly to ground instead of operating normally. Think of it like a light switch that's stuck in the 'off' position due to a wire touching metal.
The ECM monitors the fuel injector #8 control circuit voltage and current flow. It expects a specific voltage rise when commanding the injector open, then a drop when closing. A short to ground causes the voltage to collapse prematurely, indicating abnormal circuit resistance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Injector Control Voltage | 12V nominal when commanding open | Below 8V or irregular collapse indicating short |
| Injector Circuit Resistance | 2-4 ohms for solenoid coil | Below 1 ohm or near-zero indicating short path to ground |
Code P1273 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, P1273 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.