OBD-II Code P0212 — What It Means & How to Fix It

What Does This Error Mean?

P0212 means the ECM has detected a fault in the fuel injector circuit for cylinder 12. This only applies to 12-cylinder engines found in luxury and exotic vehicles. The injector circuit has an electrical problem — either in the injector itself, the wiring, or the ECM. Expect symptoms like rough idle, misfires, engine shaking, and increased fuel consumption.

Affected Models

Audi A8 L W12
Bentley Mulsanne
Ferrari 456 / 512
Lamborghini Aventador (V12)
BMW 760i (V12 engine)

Common Causes

Fuel injector on cylinder 12 has an open or shorted solenoid coil
Wiring harness to cylinder 12 injector is damaged, chafed, or melted
Corroded or loose connector at the cylinder 12 injector plug
Water or oil intrusion into the injector wiring harness
ECM injector driver circuit for cylinder 12 has failed

How to Fix It

Scan for all stored codes. Look especially for P0312 (cylinder 12 misfire) — if both codes appear together, the cylinder 12 injector is likely not firing at all.

Clearing codes without noting them first loses valuable diagnostic information.
Look up the cylinder numbering layout for your specific engine in the repair manual. On V12 engines, cylinder 12 is at the rear of one bank. On W12 engines, the layout differs.

Do not assume cylinder locations — each engine design numbers cylinders differently.
Inspect the cylinder 12 injector connector. Look for green corrosion, pushed-back pins, cracked plastic, or signs of heat damage. Clean or replace the connector as needed.

Connector damage is one of the most common and easiest fixes for injector circuit codes.
Measure injector resistance with a multimeter. Disconnect the injector and probe its two terminals. Compare the reading against the other injectors and the factory specification.

All injectors in an engine should read within about 1 ohm of each other. A big outlier points to a faulty injector.
If all injectors and wiring are good, clear the code and drive. If P0212 returns, take the vehicle to a specialist for ECM driver circuit testing.

ECM faults on luxury vehicles can be very expensive — confirm everything else first.

When to Call a Professional

Twelve-cylinder engines in luxury and exotic vehicles require specialist knowledge. Injector replacement on these engines often involves significant disassembly and special tools. Get professional diagnosis before spending money on parts — the injector may be fine and the wiring is the fault. For ECM concerns, only a brand-certified dealer or specialist should perform that diagnosis.

Frequently Asked Questions

Is P0212 only for exotic cars?

Mostly yes. Because it targets cylinder 12, P0212 only applies to 12-cylinder engines. These are found almost exclusively in luxury and exotic cars like BMW, Audi, Bentley, Ferrari, and Lamborghini. If you drive a regular car with 4, 6, or 8 cylinders, you will never see this code.

How much does it cost to fix P0212?

A fuel injector for a luxury or exotic vehicle costs $100 to $400 or more per injector. Labor can be extremely high on 12-cylinder engines — sometimes $500 to $1,000 just for access. Always get a proper diagnosis first to confirm the injector is actually faulty before paying for replacement.

Will P0212 fail an emissions test?

Yes. A stored P0212 code will cause a Check Engine Light, which automatically fails most emissions inspections. Even if the engine seems to run okay, the code must be diagnosed and cleared to pass.