Faulty cylinder 12 fuel injector with open or shorted coil; Damaged, chafed or corroded wiring between the injector and the control unit; Poor connection at the injector plug or control unit connector, such as corrosion, bent pins or loose terminals; Open circuit or short to earth or supply voltage in the injector feed or control wire; Fault in the injector driver inside the engine control unit; Blown fuse or faulty relay supplying the injector circuit, where fitted for that bank.

P0212

Cylinder 12 Injector A Circuit.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
12: FaultThe specific fault in that area

What it means

P0212 is the generic code for a fault in the injector circuit for cylinder 12. The engine control unit monitors the injector driver and wiring, and sets the code when the current or voltage it sees does not match what it expects. This points to an electrical problem in the circuit rather than proof that the injector is mechanically blocked. Only engines with twelve cylinders, such as V12s, use this code.

Symptoms

Engine warning light on
Misfire or rough running on one cylinder
Reduced power or the car going into a limited performance mode
Rough idle or hesitation under load
Smell of unburnt fuel or poor fuel economy
Engine may be hard to start

Possible causes

Faulty cylinder 12 fuel injector with open or shorted coillikely
Damaged, chafed or corroded wiring between the injector and the control unitlikely
Poor connection at the injector plug or control unit connector, such as corrosion, bent pins or loose terminalslikely
Open circuit or short to earth or supply voltage in the injector feed or control wirepossible
Fault in the injector driver inside the engine control unitrare
Blown fuse or faulty relay supplying the injector circuit, where fitted for that bankrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine speed, load and temperature when the code set. Check for other injector or misfire codes.
Check for technical service bulletins and the injector circuit layout for the specific model and engine, as wiring and bank arrangement vary.
Visually inspect the cylinder 12 injector plug, wiring and nearby loom for heat damage, chafing, oil contamination and corrosion.
Disconnect and inspect the injector connector and control unit connector for bent, pushed-back or corroded terminals, and check the terminal tension.
Measure the injector coil resistance and compare it with the manufacturer specification for that engine.
Check the injector feed voltage and the related fuses and relays, following the wiring diagram.
Test the wiring for continuity and for shorts to earth or voltage between the injector and the control unit, with the connectors disconnected.
Use a scan tool's active test, or a suitable scope, to confirm the control unit is sending a correct injector pulse and that the injector responds.

How to fix

Replace the cylinder 12 injector if its resistance is out of specification or it fails testing.
Repair or replace damaged wiring, using proper soldered and sealed joins or a new section of loom.
Clean, repair or replace corroded or damaged connector terminals and plugs.
Replace any blown fuse or faulty relay once the cause of the failure has been found.
Replace or repair the engine control unit only after all wiring and injector faults have been ruled out and the driver fault is confirmed.
Clear the code and road test to confirm it does not return.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but a dead injector causes a misfire and can let unburnt fuel reach the catalytic converters, so get it repaired soon. Avoid heavy loads and long journeys, and stop if the engine runs very roughly or the warning light flashes.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.