P0612

Fuel Injector Control Module Relay Control Circuit

Powertrain Fuel and Air Metering Fuel Injector Control Relay 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

The ECU detected a problem with the relay that controls power to the fuel injectors, similar to a light switch that's not turning on or off properly. Without proper relay control, the injectors can't receive the electrical signal needed to spray fuel into the engine.

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Symptoms You May Notice

3 known symptoms for this code
Engine cranks but won't start or starts with difficulty
Rough idle or stalling at stops
Check Engine Light illuminated with P0612
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors the fuel injector control module relay's voltage and resistance during the relay activation circuit self-test. It detects open circuits, shorts to ground, shorts to power, or relay coil faults by measuring coil voltage and circuit continuity. If voltage readings fall outside expected ranges or the relay fails to energize/de-energize on command, the fault is triggered.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Relay Coil Voltage 11-14V when activated <8V or >16V
Circuit Resistance 2-10 ohms coil resistance Open (infinite) or shorted (<0.5 ohms)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Fuel Injector Control Module Relay
Locate the relay in the engine bay fuse box (consult service manual), pull it straight out, and install the replacement relay in the same socket.
2
Engine Control Module (ECM) Connector
Disconnect the negative battery terminal, inspect the ECM connectors for corrosion or bent pins, clean with electronics cleaner, and reconnect.
3
Fuel Injector Control Module Wiring Harness
Trace the wiring from the relay to the ECM and fuel injectors for visible damage, pinched wires, or loose connectors; repair or reconnect as needed.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0612 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0612

What happens after you fix the fault

Once the fault is repaired, P0612 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.