OBD codes / P0212
P0212
SeriousInjector Circuit/Open - Cylinder 12
Twelve cylinders make one dead one easy to overlook — but cylinder 12's unburned fuel is still flowing into a catalytic converter that costs a small fortune on a V12. Fix this promptly rather than living with it; drive gently until then and stop immediately if the light flashes.
What this code means
P0212 is the highest-numbered generic injector circuit code: the engine computer detected an open circuit, a short, or out-of-range resistance in the wiring and coil that fire the cylinder 12 fuel injector. Only V12 engines have a twelfth cylinder, so this code is exclusive to twelve-cylinder luxury and performance vehicles. Like its eleven siblings, it describes an electrical failure — a clogged injector conducts electricity normally and would set misfire or fuel-trim codes instead. Diagnosis runs cheapest-first: verify the injector connector is fully seated and free of corrosion, inspect the long V12 harness for chafed or heat-hardened wiring, then resistance-test the injector's internal winding. Only after all of that checks out should the engine computer's driver stage come under suspicion, because it fails rarely. Expect the paired misfire code P0312 whenever cylinder 12 isn't firing.
Symptoms you might notice
- Cylinder 12 misfire, typically stored with P0312
- Idle vibration a V12 owner will notice immediately — these engines are normally glass-smooth
- Loss of power and refinement under acceleration
- Check-engine light, possibly flashing during the misfire
- Hard starting in some cases
What it costs to fix
Typical range: $100–$600 · about ~0.5–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Fuel injector (single) | $50–$300 | ~0.5–2 hrs |
| Wiring / connector repair | $10–$60 | ~0.5–1.5 hrs |
This code only exists on V12s, where injector access often means removing intake plumbing and where parts carry luxury-brand pricing — real-world totals can exceed these ranges, which reflect common gasoline injectors. Diesel and exotic direct-injection injectors cost far more still.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0212 for my exact vehicle →
Frequently asked
Can I keep driving my V12 with P0212?
It will drive, and probably still feel strong — that's the danger. The misfiring cylinder is loading the catalytic converter with raw fuel, and converter failure on a twelve-cylinder car is a dramatically bigger bill than an injector circuit repair. Keep driving minimal and gentle until it's fixed.
Where is cylinder 12?
It's the last cylinder in the firing count, but which physical position that is depends on the manufacturer's numbering — V12 makers number their banks differently. Consult the cylinder-layout diagram for your specific engine before removing anything.
What's the most likely cause of P0212?
Connector and wiring problems lead the list — corrosion, a half-seated plug, or a wire chafed along the long harness runs a V12 requires. A failed injector winding is next. The engine computer's driver is a genuine but rare cause, so rule out everything else first.
Would swapping injectors help before I buy one?
Yes — exchange the cylinder 12 injector with a neighbor and clear the codes. If the circuit code moves with the injector, buy the injector. If P0212 stays put, the money belongs in wiring diagnosis instead. On a V12, confirming before purchasing is especially worthwhile given parts prices.
Seeing P0212 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0212 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.