What does it mean?
P1229 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 5 Fuel Injection Circuit Short to Ground .
Symptoms
- Check engine lamp on with a cylinder 5 misfire recorded
- Rough running, vibration and a noticeable drop in power
- Rich exhaust, black smoke and fuel smell around the vehicle
- Fuel diluted oil and a fouled plug on that cylinder
- Extended cranking, and no start if the shared injector fuse has blown
Likely causes
- Chafe damage on the rear bank harness, where the loom is routed tightly against the block
- Moisture and corrosion collecting in the connector at the back of the engine
- Injector coil shorted to its own body
- Loom pinched by the intake manifold, engine cover or a wiring channel
- A previous repair splice that has lost its insulation
- Module injector driver already failed, frequently with a blown fuse
How to fix it
- Check the injector fuse and see which cylinders share it
- Disconnect the injector and measure control wire resistance to ground; a low value proves the short
- Free the rear bank harness and inspect it where it lies against the block and brackets
- Inspect the connector for water and corrosion and test each injector pin to its body
- Compare injector resistances across the engine to spot an internally shorted unit
- Repair the harness, reroute it clear of metal and confirm the circuit is clean
- Fit a new injector if it is internally shorted, and check the module driver as the final step