P0612 — Fuel Injector Control Module Relay Control

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0612 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the fuel delivery and mixture control for damage, corrosion, chafing or poor contact.
Subsystem check Measure fuel pressure at the rail and compare with factory specification at idle and under load.
Subsystem check Check short-term and long-term fuel trims in live data to see which way the mixture is off.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0612 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0612 (parts and labor, USD, independent shop rates): Replace the fuel pump: $400–$900; Replace the fuel filter: $80–$200; Replace the pressure regulator or sensor: $150–$450; Clean or replace injectors: $200–$800. Overall, fixing P0612 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How much does it cost to fix P0612?

Replace the fuel pump — $400–$900; Replace the fuel filter — $80–$200; Replace the pressure regulator or sensor — $150–$450; Clean or replace injectors — $200–$800. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Is it safe to drive with P0612?

Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

What is the most common cause of P0612?

The most common causes are: clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring.

What are the symptoms of P0612?

Drivers most often notice: rough idle and hesitation, fuel smell in severe cases, loss of power under load, hard starting or long cranking.

What does OBD2 code P0612 mean?

Fuel Injector Control Module Relay Control (P0612): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring.

When your check engine light comes on and a scan tool reveals P0612, the powertrain control module has detected a problem with the fuel injector control module relay circuit. This is not a sensor failure in the traditional sense — the module responsible for operating the fuel injectors is reporting abnormal behavior from its own relay control circuit. Think of it as the brain having trouble sending the "on" command to the fuel delivery system.

The engine control unit runs constant self-checks while the engine is running. P0612 triggers when voltage or ground signals at the fuel injector control circuit fall outside factory specifications for more drive cycles than the system allows. The trouble code also locks in freeze frame data — a snapshot of engine speed, load, temperature, and vehicle speed at the exact moment the fault appeared. That snapshot is your best clue for reproducing the failure condition during testing.

Common Symptoms of P0612

The P0612 fault code rarely appears alone. Watch for these clues alongside the illuminated check engine lamp:

Rough idle and noticeable hesitation during acceleration
Strong fuel odor, especially at higher concentrations
Noticeable loss of power when the engine is under load
Extended cranking time before the engine starts
Fuel economy dropping below your normal range
Check Engine Light remaining solid or flashing under severe conditions

Typical Causes

Not every P0612 stems from the same root problem. The most frequent culprits involve anything that disrupts the precise fuel delivery the control module expects:

Dirty or clogged fuel injectors restricting spray pattern
Leaking fuel injectors dumping raw fuel into the cylinder
Faulty fuel pressure regulator allowing pressure to drift out of spec
Vacuum leaks downstream of the throttle body introducing unmetered air
Weak or failing fuel pump unable to maintain adequate rail pressure
Clogged fuel filter restricting flow under demand conditions
Contaminated or incorrect fuel grade affecting combustion

How to Diagnose P0612

Proper diagnosis keeps you from throwing parts at the problem. Follow these steps in order:

Connect your OBD2 scanner and confirm P0612 is stored. Record the freeze frame data before clearing anything — that record shows exactly what the engine was doing when the failure occurred.
Scan for any additional trouble codes. Related codes pointing to fuel pressure, O2 sensors, or mass airflow often expose the real cause behind P0612. Check manufacturer TSB databases for known software updates or campaigns for your specific make.
Inspect all wiring and connectors tied to the fuel injector control circuit. Look for chafed insulation, corrosion at the terminals, and any connectors that are loose or damaged.
Measure fuel pressure at the fuel rail with a gauge. Compare your readings against factory specifications at idle, at cruise, and under vacuum spike. Low pressure points to pump or regulator issues; pressure that climbs excessively suggests a stuck regulator.
Monitor short-term and long-term fuel trims using your scanner's live data. Positive trims indicate the PCM is adding fuel to compensate for a lean condition; negative trims show it's pulling fuel for an overly rich mixture.
Clear the code and complete a full drive cycle that mirrors the freeze frame conditions. If P0612 returns, you have confirmed an active fault rather than a one-time glitch.

Repair Options and Costs

Repair costs vary widely depending on which component is actually responsible. Start with the cheapest probable causes before committing to major repairs:

Fuel filter replacement — $80–$200
Fuel pressure regulator or sensor replacement — $150–$450
Fuel injector cleaning or replacement — $200–$800
Fuel pump replacement — $400–$900

Most independent shops charge these labor rates plus parts. A proper diagnosis before purchasing any parts typically saves far more than the cost of the diagnostic time itself. The most expensive fix is rarely the first one you should pursue.

Can You Drive with P0612?

Treat P0612 with caution. Fuel delivery and mixture problems can lead to stalling at low speeds, unpredictable hesitation when merging or passing, and in prolonged cases, unburned fuel washing past the catalytic converter — potentially destroying it. Avoid extended highway trips until you have identified and resolved the underlying cause.