Ford fault codes
Ford's modular V8s (4.6/5.4 Triton), 3.5/3.7 Duratec V6s and turbocharged EcoBoost engines have well-documented, predictable fault patterns. Coil-on-plug failures, PCV and intake-boot leaks, and EVAP purge issues lead the list across the F-150, Mustang, Explorer, Escape, Fusion and Focus. Most are DIY-friendly once you know where these engines typically fail.
Ford-specific diagnostic tips
- Coil-on-plug (COP) failure is the classic Ford misfire cause. Swap the suspect coil to another cylinder and see if the misfire follows it. Motorcraft coils and plugs are the dependable fix.
- Lean codes (P0171/P0174) on EcoBoost and modular engines usually trace to a torn PCV hose, a cracked intake elbow or boot, or a dirty MAF. Check the rubber before buying sensors.
- On 5.4L 3-valve Tritons, use the correct one-piece plugs and follow Ford's removal procedure. The early two-piece plugs are notorious for breaking off in the cylinder head.
- EVAP codes (P0440/P0442/P0455/P0456) often come down to the fuel cap and the purge/vent valves, so check those before dropping the tank.
In-depth Ford code guides
Hand-researched, Ford-specific diagnosis, costs and fixes.
P0171 System Too Lean on Ford: Causes, Fixes & Cost
Ford
P0300 Random Misfire on Ford: Causes, Fixes & Cost
Ford
P0301 Cylinder 1 Misfire on Ford: Causes, Fixes & Cost
Ford
P0420 on Ford: Catalyst Efficiency Below Threshold — Causes, Fixes & Cost
Ford
P0440 EVAP System Malfunction on Ford: Causes, Fixes & Cost
Ford
Common codes on Ford
Generic OBD-II codes our guides flag as common on Ford vehicles.
Left Front Wheel Speed Sensor Circuit
Exhaust Camshaft Timing Over-Advanced (Bank 1)
Crankshaft/Camshaft Position Correlation (Bank 1, Sensor A)
Crankshaft/Camshaft Position Correlation (Bank 1, Sensor B)
Mass Air Flow (MAF) Sensor Range/Performance Problem
Mass Air Flow (MAF) Sensor Circuit Low Input
Intake Air Temperature (IAT) Sensor Circuit High
Engine Coolant Temperature (ECT) Sensor Circuit High
Insufficient Coolant Temperature for Closed Loop
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
O2 Sensor Slow Response (Bank 1, Sensor 1)
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
System Too Lean (Bank 1)
System Too Rich (Bank 1)
System Too Lean (Bank 2)
System Too Rich (Bank 2)
Throttle/Pedal Position Sensor B Circuit High
Turbocharger/Supercharger Overboost Condition
Turbocharger/Supercharger Underboost Condition
Random/Multiple Cylinder Misfire Detected
Cylinder 1 Misfire Detected
Cylinder 2 Misfire Detected
Cylinder 3 Misfire Detected
Cylinder 4 Misfire Detected
Cylinder 5 Misfire Detected
Cylinder 6 Misfire Detected
Camshaft Position Sensor Circuit Malfunction
Camshaft Position Sensor Range/Performance
Exhaust Gas Recirculation (EGR) Flow Insufficient
Catalyst System Efficiency Below Threshold (Bank 1)
Catalyst System Efficiency Below Threshold (Bank 2)
EVAP System Malfunction
EVAP System Small Leak Detected
EVAP Leak Detected (Loose/Faulty Fuel Cap)
Engine Oil Pressure Sensor Range/Performance
System Voltage High
ECM/PCM Processor Fault
Transmission Control System Malfunction
Torque Converter Clutch Circuit Malfunction
Torque Converter Clutch Performance / Stuck Off
Post-Catalyst Fuel Trim System Too Lean (Bank 1)
O2 Sensor Signal Stuck Lean (Bank 1, Sensor 1)
Lost Communication With ECM/PCM A
Lost Communication With TCM