Faulty fuel injector control module relay (worn contacts or failed coil); Corroded, loose or damaged connectors or terminals at the relay, relay socket or fuse box; Open circuit or chafed wiring in the relay control or supply circuit; Blown fuse or poor power or earth supply to the relay or injector control module; Low battery voltage or charging system fault causing unstable supply; Faulty fuel injector control module or internal PCM driver fault; Outdated PCM software where the manufacturer has issued a known fix for the model.

P0612

Fuel Injector Control Module Relay Control.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
12: FaultThe specific fault in that area

What it means

P0612 means the powertrain control module has detected a fault in the control circuit for the relay that supplies power to the fuel injector control module. The PCM commands the relay and monitors the circuit, and it saw a result that did not match, such as an open circuit, a short or no response. The exact relay arrangement and the type of fuel injector control module vary by vehicle and engine.

Symptoms

Engine cranks but will not start
Intermittent stalling or cutting out while driving
Misfire or rough running
Reduced power or limp mode
Engine warning light on
Hard starting when hot or after sitting

Possible causes

Faulty fuel injector control module relay (worn contacts or failed coil)likely
Corroded, loose or damaged connectors or terminals at the relay, relay socket or fuse boxlikely
Open circuit or chafed wiring in the relay control or supply circuitpossible
Blown fuse or poor power or earth supply to the relay or injector control modulepossible
Low battery voltage or charging system fault causing unstable supplypossible
Faulty fuel injector control module or internal PCM driver faultrare
Outdated PCM software where the manufacturer has issued a known fix for the modelrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including battery voltage and engine state when the fault set.
Check battery condition and charging voltage, as low or unstable voltage can trigger relay circuit faults.
Visually inspect the relevant fuses, relay, relay socket and fuse box for corrosion, heat damage, water ingress and poor terminal tension.
Identify the correct relay and circuit using the wiring diagram for the specific model and engine, as the layout differs between vehicles.
Check the relay operation by listening for it clicking and testing the coil resistance and contact continuity against specification, or swap with a known good identical relay.
Test the relay supply, control signal and earth with a multimeter, and wiggle test the harness to find intermittent faults.
Check the wiring between the relay, the PCM and the injector control module for open circuits, shorts to earth or shorts to voltage.
If the circuit and relay prove good, check for manufacturer software updates and then consider the control module itself.

How to fix

Replace the faulty relay with one of the correct specification.
Clean or repair corroded terminals and connectors, or replace the damaged relay socket or fuse box section.
Repair or replace damaged wiring in the relay control or supply circuit.
Replace any blown fuse after finding and correcting the cause of the overload.
Repair the battery or charging system fault if voltage is low or unstable.
Update the PCM software if a known fault is documented, or repair or replace the control module if it is confirmed faulty.

Can I keep driving?

High severity

Avoid driving the car if it is stalling, misfiring or in limp mode, as it could cut out without warning in traffic. If it runs normally, only drive it a short distance to get it repaired promptly.

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