What does it mean?
P1226 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 2 Fuel Injection Circuit Short to Ground .
Symptoms
- Check engine lamp on, with a misfire recorded for cylinder 2
- Rough idle, vibration and an obvious dead or weak cylinder
- Excessive fuelling on that cylinder, black smoke and a strong fuel smell
- Fuel diluting the engine oil, so the level rises and the oil thins
- Hard starting, poor drivability and a blown injector fuse in some cases
Likely causes
- Insulation worn through where the injector wire rests on the cylinder head or a metal rail
- Water or coolant sitting in the injector connector
- Internal short from the injector coil to its metal body
- Harness crushed by a bracket, clamp or engine cover fixing
- Rodent or heat damage exposing the copper of the control wire
- Failed module driver stage, often accompanied by a blown fuse
How to fix it
- Check the injector circuit fuse and note whether other injectors have gone dead with it
- Disconnect the injector and measure from the control wire to ground; near zero resistance proves the short
- Follow the harness and look for the point where it touches metal, especially around the head and manifold
- Inspect the connector for moisture and corrosion and test the injector pins to its body
- Compare all injector resistance values to identify an internally shorted unit
- Repair and reroute the wiring, then confirm the short has gone before replacing components
- Fit a new injector if it tests shorted, and check the module output stage only afterwards