What does it mean?
P1261 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: High Voltage Circuit Fault – Cylinders 1, 4, 6, and 7 .
Symptoms
- The MIL is on, often flashing when the misfire is heavy
- Rough running with misfire felt from several cylinders at the same time
- Hard starting or extended cranking, sometimes a no start
- Significant power loss and heavy vibration at idle
- Fuel smell from the exhaust and higher consumption
- Engine may run on the remaining cylinders only, sounding uneven
Likely causes
- Short between the high side feed and a low side driver wire inside the loom for that injector group
- Chafed injector harness under the intake manifold or against a cylinder head bracket
- Water or oil intrusion in the injector group connector creating a leakage path
- Shorted injector winding in one of the four cylinders dragging the shared feed down
- Failed injector driver stage in the module for that group
- Poor ground or a weak supply feed shared by the group
- Previous repair with incorrect wire splicing or the wrong injectors fitted
How to fix it
- Check which cylinders are misfiring on live data and confirm they match the affected group
- Inspect the injector harness for chafing, melted insulation and connector damage, especially where it passes under or beside the manifold
- Unplug all injectors in the group and measure each winding resistance, comparing them with each other and with specification
- Test each injector circuit for insulation to ground and for shorts between the feed and driver wires
- Reconnect the injectors one at a time to identify which one pulls the circuit down
- Check the module connector pins for burning and confirm the group supply and ground are clean
- Replace the shorted injector or repair the harness, then clear codes and confirm all cylinders contribute equally on the misfire counters