Injector High Sides Shorted Together
Two fuel injector high-side driver circuits are electrically connected when they shouldn't be, like two light switches wired together so flipping one affects the other. This prevents the ECU from controlling the injectors independently.
The ECU monitors the voltage and current signals from each injector's high-side driver circuit. It detects when two driver outputs are shorted together by observing abnormal voltage levels that don't match expected switching patterns. The fault triggers when the ECU cannot independently control injector firing on affected cylinders.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| High-side driver output voltage | 12V battery voltage when off, 0V during switching pulse | Voltage collapse or cross-talk between two driver circuits |
| Driver current draw | Individual injector current isolation | Abnormal current path between two high-side outputs |
Code P1302 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, P1302 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.