What does it mean?
P1216 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 4 Fuel Injection Circuit Short to B+ .
Symptoms
- Check engine lamp on, sometimes flashing under load
- Persistent misfire on cylinder 4 with rough idle
- Strong fuel smell, black exhaust smoke and rising consumption
- Fuel in the engine oil, raising the level and thinning the oil
- Hard starting and stalling when coming to a stop
Likely causes
- Rubbed-through insulation where the injector branch of the loom is clipped alongside a battery feed
- Water or oil pooling in the connector, bridging pins internally
- Injector coil shorted to its own supply terminal
- Loom crushed by a fastener, a heat shield edge or the intake being refitted incorrectly
- Damaged terminal seals allowing washing water into the circuit
- Injector driver in the module already failed short
How to fix it
- Record all codes and check whether neighbouring cylinders are also reported
- Disconnect the injector, switch the ignition on and measure the control wire against ground
- Inspect the harness branch that feeds cylinder 4 for chafe, crush marks and melted insulation
- Dry the connector, clean the terminals and measure between the control and supply pins
- Compare injector resistance readings across the engine and check winding to supply insulation
- Repair the harness, clear the codes and confirm the misfire counter stays at zero
- Replace the injector only if it tests shorted, and check the module driver after the circuit is repaired