High5.0L Cummins

0612 Nissan Titan XD 5.0L Cummins — Fuel Injector Con (2026)

0612 on Nissan Titan XD 5.0L Cummins means fuel injector control module relay control. 10–15% of field cases trace to failed ficm power relay. Shop repair with parts runs $15 - $600; DIY wiring or filter work starts at $40–$150. Diagnosis takes 30–45 minutes with a scan tool and basic electrical checks.

What This Code Means

0612 on Nissan Titan XD 5.0L Cummins tells the ECM that fuel injector control module relay is outside calibrated limits. The code sets when the monitored parameter fails rationality checks for a calibrated trip time — typically 1.4–4 seconds continuous on OBD-II diesel platforms. P0612 on the Nissan Titan XD ISV5.0 indicates the ECM cannot properly control power to the fuel injector control module through its relay circuit. ProfessionalDieselRepair.com tests the FICM relay and fuse first on P0612 no-start calls — most failures are simple power delivery problems rather than a failed injector driver module.

Common Symptoms

• Check engine light with possible no-start or rough running (100% of cases)
• FICM power relay may not click when key is cycled to on (80% of cases)
• Injector control module may show no communication in Cummins INSITE (60% of cases)
• Engine may crank normally but fail to fire if FICM power is absent (40% of cases)
• Possible companion codes related to injector circuit or FICM communication (25% of cases)

Likely Causes (Ranked by Probability)

1. Failed FICM power relay (45% of cases) — Relay coil or contact failure prevents the ECM from switching power to the injector control module.

2. Blown fuse in the FICM relay supply circuit (25% of cases) — A short downstream or aged fuse opens the circuit, removing FICM power and setting P0612.

3. Open or corroded control wiring between ECM and relay (15% of cases) — Harness damage or corroded relay socket pins prevent reliable relay engagement.

Step-by-Step Diagnostic Guide

1. Scan with Cummins INSITE or Jaltest and confirm P0612 with any related FICM or injector codes. — Tool: scan tool or multimeter. Document readings on the work order.

2. Locate the FICM relay in the underhood fuse box. Swap with an identical relay to test quickly. — Tool: scan tool or multimeter. Document readings on the work order.

3. Check the fuse protecting the FICM relay circuit. Replace any blown fuse only after identifying why it failed. — Tool: scan tool or multimeter. Document readings on the work order.

4. With key on, verify battery voltage at the relay output terminal when the relay is commanded. No voltage indicates relay or control circuit failure. — Tool: scan tool or multimeter. Document readings on the work order.

5. Inspect wiring from the ECM to the relay and from the relay to the FICM for opens, corrosion, or damage. Repair harness faults before replacing the FICM. — Tool: scan tool or multimeter. Document readings on the work order.

Repair Options (with Costs)

Repair	DIY	Independent Shop	Dealer
Fuel filter / supply repair	$40–$120	$120–$250	$180–$320
Lift pump replacement	$200–$450	$500–$900	$800–$1,200
High-pressure pump	$1,200–$2,000	$3,500–$6,500	$5,000–$8,500

Platform-Specific Notes

5.0L Cummins (2016–2022): Common-rail — Follow nissan-titan-xd OEM diagnostic tree for 0612 on 5.0L Cummins.

When This Code Sets

0612 typically stores after the ECM detects fuel injector control module relay outside calibrated limits for 1.4–4.0 seconds (OBD-II trip). Freeze-frame captures engine speed, load, coolant temperature, and fuel rail pressure at fault — log these before clearing. Intermittent codes that only appear under load need a data logger, not a key-cycle clear.

Scan Tool Parameters to Log

• Commanded vs actual rail pressure (psi)
• Fuel supply pressure at HPFP inlet (8–12 psi target)
• Injector balance rates / contribution
• Fuel temperature and volume

Common Misdiagnoses

Parts-cannon FICM replacement when the relay or fuse never supplied power — No-start with injector codes points attention to the FICM itself.. Instead: Swap the relay, verify the fuse, and measure voltage at the FICM power feed with key on before ordering a module.

Replacing injectors for a relay control electrical fault — Misfire or no-start symptoms are attributed to fuel injectors.. Instead: Confirm FICM power and communication in Cummins INSITE. Injectors cannot operate without a powered and communicating FICM.

Shop Notes from the Field

Shop tip: ProfessionalDieselRepair.com swaps the FICM relay and checks its fuse before any FICM replacement on Titan XD P0612 calls. A $20 relay fix resolves most no-start cases — a parts-cannon FICM order is avoided when power never reached the module because of a blown fuse or corroded relay socket.

Safety Warning

• Disconnect batteries before working on FICM connectors or high-pressure fuel components.
• Do not bypass fuses with higher amperage ratings — find and repair the short that blew the original fuse.
• Relieve fuel system pressure per service manual if fuel lines near the FICM are disturbed.

Prevention Tips

• Replace aging relays in the underhood fuse box during major service.
• Inspect relay socket terminals for corrosion on high-mileage trucks.
• Address water intrusion in the fuse box after cab washing or flood exposure.

Nissan Titan XD Field Notes for 0612

• Capture a 20-minute data log of fuel injector control module relay parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
• Check for OEM technical service bulletins covering 0612 on 5.0L Cummins — many bulletin fixes address harness routing rather than sensor replacement.
• Torque fuel injector control module relay mounting fasteners per Nissan Titan XD OEM spec — verify with engine serial. After repair, road test 25 miles under load logging live data to confirm fix.
• Document ambient temperature and key-cycle count at fault set on Nissan Titan XD 5.0L Cummins — cold-soak faults on fuel injector control module relay often clear after warm-up when moisture is the root cause.
• Compare this unit’s repair history: repeat 0612 within 5,000 miles indicates incomplete prior repair, not a new component failure.
• If fuel injector control module relay was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on Nissan Titan XD.
• Capture a 20-minute data log of fuel injector control module relay parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
• Check for OEM technical service bulletins covering 0612 on 5.0L Cummins — many bulletin fixes address harness routing rather than sensor replacement.
• Torque fuel injector control module relay mounting fasteners per Nissan Titan XD OEM spec — verify with engine serial. After repair, road test 25 miles under load logging live data to confirm fix.
• Document ambient temperature and key-cycle count at fault set on Nissan Titan XD 5.0L Cummins — cold-soak faults on fuel injector control module relay often clear after warm-up when moisture is the root cause.
• Compare this unit’s repair history: repeat 0612 within 5,000 miles indicates incomplete prior repair, not a new component failure.
• If fuel injector control module relay was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on Nissan Titan XD.

Related Codes

• P0611 — often stacks with 0612
• P0201 — often stacks with 0612
• P0562 — often stacks with 0612

FAQ

What does P0612 mean on a Nissan Titan XD?

P0612 means the ECM detected a fault in the fuel injector control module relay control circuit. The FICM may not receive power, causing no-start or misfire conditions.

Where is the FICM relay on the Titan XD?

The FICM power relay is in the underhood fuse and relay box. Consult the lid diagram or service manual for the exact location on your model year.

Can a bad relay cause a no-start?

Yes. Without relay power, the FICM cannot drive the injectors and the engine will crank without firing even with good fuel pressure.

What does 0612 mean on Nissan Titan XD 5.0L Cummins?

0612 means fuel injector control module relay control. The ECM detected fuel injector control module relay outside calibrated limits. Verify with freeze-frame data before clearing.

Can I drive with 0612 active?

Short distances only if power is normal. Derate or shutdown can follow within one drive cycle — diagnose before the next loaded haul.

How much does it cost to fix 0612?

DIY repairs start at $40–$150 for wiring or filters. Shop repairs with parts run $15 - $600. Dealer pricing runs $200 - $500.

What is the most common cause of 0612?

Failed FICM power relay — confirm with visual inspection and live data before ordering parts.

Sources

• OEM service information — Nissan Titan XD 5.0L Cummins diagnostic procedures
• SAE J2012 — OBD-II DTC definition for 0612
• Mitchell1 ProDemand — 2026 labor and parts cost surveys

Related Reading

• Nissan Titan XD fault codes hub
• Diesel repair cost estimator
• Fuel Injector Control Module Relay diagnostic guide
• P0611
• P0201