2013 Lincoln Nautilus P0173 — FUEL TRIM MALFUNCTION BANK 2 Diagnosis & Fix

When your 2013 Lincoln Nautilus illuminates the check engine light and displays diagnostic trouble code P0173, it indicates a specific problem with the Fuel trim malfunction bank 2. This comprehensive guide walks you through the diagnostic process, common causes, and proven repair solutions for your Lincoln.

Understanding P0173 in Your 2013 Nautilus

The On-Board Diagnostics II (OBD-II) system in your 2013 Lincoln Nautilus monitors virtually every aspect of engine and transmission operation. When the PCM (Powertrain Control Module) detects a malfunction that exceeds acceptable parameters, it stores a diagnostic trouble code and illuminates the MIL (Malfunction Indicator Lamp).

The 2013 Nautilus features Ford's advanced engine management system working in conjunction with the PCM (Powertrain Control Module). When the P0173 code appears, it indicates a problem with the Fuel trim malfunction bank 2 that can affect fuel delivery, air-fuel mixture, and overall engine performance. The EcoBoost engines in particular utilize high-pressure fuel injectors and precise MAF (Mass Air Flow) sensing for optimal power delivery.

Modern Lincoln vehicles employ a returnless fuel system design that reduces fuel heating and vapor lock potential. The fuel pump driver module controls fuel pump speed based on engine demand, working with the PCM to maintain proper fuel pressure across the direct injection and port injection systems.

Common causes include faulty sensors, wiring harness damage from road debris, vacuum leaks in the intake manifold, and occasionally PCM software issues that require reflashing at your Lincoln dealer.

Common Symptoms of P0173

Your Nautilus may exhibit one or more of the following symptoms when P0173 is active:

• Illuminated check engine light (MIL)
• Rough idle or engine hesitation
• Decreased fuel economy
• Reduced engine power/performance
• Unusual noises from the engine compartment
• Transmission shifting issues
• Stability control warning light
• ABS system malfunction

Diagnostic Procedure for P0173

Step 1: Retrieve Freeze Frame Data

Connect your OBD-II scanner to the data link connector (DLC) located beneath the dashboard on the driver's side. Record all stored diagnostic trouble codes and freeze frame data. This information reveals the exact operating conditions when the malfunction first occurred, including:

• Engine temperature
• Vehicle speed
• RPM range
• Open/closed loop status
• Fuel trims

Step 2: Visual Inspection

Perform a thorough visual inspection of related components:

• Check all vacuum lines for cracks, disconnections, or damage
• Inspect wiring harnesses for chafing, broken wires, or corrosion
• Verify proper connection of all electrical connectors
• Look for signs of fluid leaks that could affect sensors
• Check grounds for proper attachment and cleanliness

Step 3: Component Testing

Using a digital multimeter and oscilloscope, test the specific component indicated by the code:

• Measure voltage and ground signals
• Check resistance values against specifications
• Test operation under load conditions
• Verify CAN communication if network code

Step 4: Clear and Verify

After repairs, clear the code and perform a test drive under conditions matching the freeze frame data. The code should not return, confirming successful repair.

Estimated Repair Costs for P0173

1-2 hours

Prevention Tips for Lincoln Nautilus Owners

To minimize the risk of P0173 and other diagnostic trouble codes in your 2013 Nautilus:

1. Follow maintenance intervals — Regular oil changes, air filter replacements, and spark plug updates prevent many issues.

2. Use quality fuel — Top-tier gasoline prevents fuel system deposits and maintains proper fuel pump operation.

3. Address warning lights immediately — Ignoring check engine lights can lead to more serious and expensive repairs.

4. Keep connectors clean — Battery terminal corrosion and dirty electrical connections cause numerous electrical issues.

5. Protect wiring — Inspect wiring harnesses after off-road driving or when installing accessories.

When to Seek Professional Help

While many Nautilus owners successfully diagnose and repair P0173 themselves, certain situations require professional assistance:

• Network communication codes (U-codes) typically require specialized diagnostic equipment
• Transmission-related codes may require transmission-specific expertise
• If multiple codes are present, the root cause may be difficult to isolate
• When repairs involve PCM reflashing or module programming

Conclusion

Understanding P0173 in your 2013 Lincoln Nautilus empowers you to make informed decisions about diagnosis and repair. Whether you tackle this as a DIY project or visit your local Lincoln dealer, addressing this code promptly prevents further damage and restores your vehicle's optimal performance.

For more Lincoln diagnostic guides and maintenance tips, explore our comprehensive collection of OBD-II code explanations tailored specifically for Lincoln vehicles.