P0612: Fuel Injector Control Module Relay Control

What it means

A fault has been detected in the fuel injector control module relay control. The code does not identify whether the fault is in the relay, its wiring, or its control.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The fuel injector control module relay supplies or enables power for the injector control system, while a control circuit commands the relay. P0612 sets when the module detects a fault in that relay-control function; the fault may be the relay, its wiring or connector, or the module's relay driver.

Common causes

Most likely first.

1. Fuel-injector control-module relay fault
2. Open, shorted, or high-resistance relay-control wiring
3. Poor relay or module connector contact
4. Fault in the control module’s relay driver

Symptoms

• Check engine light on
• Misfire or rough idle on the affected cylinder
• Increased fuel consumption
• Possible fuel smell or smoke from exhaust

How to diagnose it

1. Save freeze-frame data and scan for injector-control, misfire, and voltage faults to see whether relay control is disrupting injector operation.
2. Locate the relay and control module using the vehicle's wiring information, then inspect the relay, socket, and connectors for corrosion, heat damage, or loose terminals.
3. Check the relay coil and switched contacts using the manufacturer's procedure, and verify that the relay receives the required supply and ground.
4. Test the relay-control wire between the module and relay for opens, shorts, or excessive resistance, and check for a reliable module power and ground.
5. If the relay and circuit test correctly, follow the manufacturer's procedure to assess the control module's relay command and driver, including any applicable software updates.

Common fixes

• Clean and secure relay or module connector contacts.
• Repair open, shorted, or high-resistance relay-control wiring.
• Replace the injector control module relay if it fails the manufacturer's test.
• Repair or replace the module only if the relay-driver output is confirmed faulty after circuit and power checks.

Can I keep driving?

If the engine misfires, stalls, or smells of fuel, avoid driving because injector power may be unreliable and unburned fuel can damage the catalytic converter. Stop if the engine runs rough or the warning light flashes.