Ford OBD Codes
decoded & explained
The codes Ford owners actually see — EGR, O2 sensors, catalysts and misfires — with clear causes and fixes.
Ford check engine light codes
Ford uses standard OBD-II engine codes, readable with any scanner. Ford’s IDS/FDRS tools add module-level diagnostics, but engine codes are fully generic.
Here are the codes most reported on Focus, Fiesta, Mondeo, F-150, Ranger and Transit models.
OBD-II code decoder
—
—
—
Most common Ford
Classic Ford faults behind these codes.
| Code | Description |
|---|---|
| P0171 | System Too Lean (Bank 1) |
| P0300 | Random/Multiple Cylinder Misfire |
| P0401 | EGR Flow Insufficient |
| P0402 | EGR Flow Excessive |
| P0420 | Catalyst System Efficiency Below Threshold (Bank 1) |
| P0442 | EVAP System Small Leak Detected |
| P0455 | EVAP System Large Leak |
| P1131 | HO2S Insufficient Switching (Bank 1, Sensor 1) |
Common Ford faults
Classic Ford faults behind these codes.
EGR flow (P0401) and excessive flow (P0402) — the EGR valve and DPFE sensor are classic Ford weak points.
O2 sensor switching (P1131) — a slow upstream sensor on petrol models.
EVAP leaks (P0442/P0455) — fuel cap, hoses or purge valve.
Catalyst efficiency (P0420) — aging converter on high-mileage models.
Misfires (P0300) — coils and plugs, common across the range.
Ford FAQ
Why is my Ford showing P0401?
What is P0402?
Why does my Ford misfire?
Are OBD codes the same across Ford models?
Can I read Ford codes without a dealer?
Codes vary slightly by model, year and engine. Always confirm with a proper diagnosis. Manufacturer-specific codes (P1xxx/P2xxx) may differ from generic descriptions.
Continue reading
Stop Coding Alone: OPC-Skills Gives Your AI Agent Superpowers
OpenClaw: Build Your Personal AI Assistant in Minutes
Top 20 AI Tools Every Developer Should Know in 2026
GibsonAI/memori: Structured Memory Infrastructure for Production AI Agents
Decode your Ford code now
Use the free decoder below, or browse the most common Ford codes.