What does it mean?
P1228 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 4 Fuel Injection Circuit Short to Ground .
Symptoms
- Check engine lamp on and misfire counters climbing on cylinder 4
- Rough idle, shaking and a hollow, uneven exhaust note
- Rich mixture, sooty or wet plug and black smoke
- Fuel smell and fuel contaminated engine oil
- Blown injector fuse in some cases, leaving several cylinders without supply
Likely causes
- Rubbed insulation where the injector wire crosses the cylinder head or a mounting stud
- Coolant leak or water intrusion into the injector connector providing a path to earth
- Injector with an internal short between winding and body
- Loom squashed under a fixing during a previous service
- Heat damage next to the exhaust side, hardening and cracking the insulation
- Failed injector driver in the module after the short has been present for some time
How to fix it
- Check the injector fuse and record which cylinders are affected
- Unplug the injector and measure the control wire to ground; a very low reading confirms the fault
- Inspect the loom where it passes the head, the exhaust side and any bracket for chafe and heat damage
- Check the connector for coolant, corrosion and melted terminals, then test injector pin to body
- Ohm all injectors and compare the readings
- Repair the harness, secure it clear of metal edges and confirm the short has gone
- Replace a shorted injector, then verify the module driver output before returning the vehicle