What does it mean?
P1265 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 5 High To Low Side Short .
Symptoms
- The MIL is on and may flash while the misfire is active
- Cylinder 5 misfire with a persistent shake at idle
- Hesitation and reduced power when accelerating
- Fuel smell from the exhaust and higher consumption
- Uneven running that gets worse as the engine warms up
- Possible popping or spitting sound from the exhaust
Likely causes
- Feed and driver wires for cylinder 5 touching where the insulation has rubbed through
- Cylinder 5 injector with an internally shorted winding
- Oil, coolant or washer fluid inside the injector connector bridging the terminals
- Harness routed against a sharp edge or hot component near the cylinder head
- Terminals in the connector spread or corroded so they arc and weld together
- Badly insulated repair joint or a wire pulled into the wrong cavity
- Module driver stage damaged after running with the short present
How to fix it
- Check misfire counters on live data and confirm cylinder 5 is the only one affected
- Unplug the cylinder 5 injector connector and inspect the terminals for oil, moisture and corrosion
- Measure the injector winding resistance and compare it with the other injectors
- With both ends disconnected, test the two circuit wires for a short to each other and for insulation to ground
- Follow the loom along the cylinder head looking for rub marks and melted insulation
- Swap the injector to a different cylinder to see whether the fault follows the component
- Repair the harness or fit a new cylinder 5 injector, then clear codes and verify no misfire counts return on a road test