P0612 means the engine computer has detected a fault in the low-side control circuit for the relay that powers the fuel injector control module. When this circuit fails, the relay may not close or its operation cannot be verified, which can prevent injector control. The code indicates an electrical problem in the relay control path rather than a mechanical injector failure.
The relay coil or contacts can fail from heat and age, so the PCM cannot energize or verify the relay and sets P0612.
Opens, shorts to ground or power, corrosion, or pin damage in the relay coil control wire or power and ground paths disrupt relay operation.
A blown fuse, fusible link, or loose ground feeding the relay or control module removes voltage needed for relay control and feedback.
If the FICM draws excessive current, has internal damage, or returns an unexpected feedback signal, the PCM may flag the relay control circuit.
Although uncommon, the internal transistor or driver that grounds the relay coil can fail; this should only be considered after wiring, relay, fuses, and module are ruled out.
Usually no. The PCM driver is rarely the actual cause; start with the relay, fuses, wiring, and fuel injector control module before considering a PCM replacement.
Yes. If the relay that powers the fuel injector control module does not close, the injectors may not operate and the engine can crank but not start or stall immediately.
No. P0612 refers to the relay control circuit for the injector control module, not a fault in a single injector coil or its wiring.
Severely low system voltage can cause relay control and communication faults, but the code usually persists due to a relay, wiring, or module problem once voltage is restored.