OBD Error Codes Explained: Complete List with Meanings (With Diagrams) Manualsbay
Modern vehicles use On-Board Diagnostics (OBD) systems to monitor engine, transmission, emissions, and electronic components. When a fault is detected, the system generates an OBD error code that helps identify the exact problem area.
This complete guide explains what OBD codes are, how to read them, their categories, and a detailed list of common OBD error codes with meanings, along with visual diagrams for easy understanding.
If you want correct repair procedures instead of guesswork, ManualsBay.com provides official factory service manuals and workshop manuals trusted by professionals worldwide.
What Is OBD / OBD-II?
OBD (On-Board Diagnostics) is a vehicle’s self-diagnostic system.
✅ Monitors engine & emission systems
✅ Stores fault codes when something fails
✅ Helps technicians & DIY users diagnose problems
✅ OBD-II is mandatory in most vehicles after 1996
How OBD Error Codes Work (Diagram Explanation)
When a fault occurs:
✅ Sensors detect abnormal readings
✅ ECU (Engine Control Unit) logs the fault
✅ A warning light (Check Engine / ABS / Airbag) turns ON
✅ Code can be read using an OBD scanner
Structure of an OBD Error Code (Example: P0301)
Each OBD code has 5 characters:
✅ 1st letter – System type
P = Powertrain (Engine & Transmission)
B = Body
C = Chassis
U = Network / Communication
✅ 2nd digit
0 = Generic (same for all brands)
1 = Manufacturer-specific
✅ Last digits – Specific fault description
Complete List of Common OBD Error Codes & Meanings
🔧 Powertrain Codes (P-Codes)
✅ P0100 – Mass Air Flow (MAF) Sensor Circuit Malfunction
✅ P0110 – Intake Air Temperature Sensor Circuit Fault
✅ P0171 – System Too Lean (Bank 1)
✅ P0172 – System Too Rich (Bank 1)
✅ P0300 – Random / Multiple Cylinder Misfire
✅ P0301 – P0308 – Misfire Detected in Specific Cylinder
✅ P0325 – Knock Sensor Circuit Malfunction
✅ P0401 – EGR Flow Insufficient
✅ P0420 – Catalytic Converter Efficiency Below Threshold
✅ P0500 – Vehicle Speed Sensor Malfunction
⚙ Transmission & Drivetrain Codes
✅ P0700 – Transmission Control System Malfunction
✅ P0715 – Input / Turbine Speed Sensor Malfunction
✅ P0720 – Output Speed Sensor Circuit Error
✅ P0730 – Incorrect Gear Ratio
🚗 Chassis Codes (C-Codes)
✅ C0035 – Wheel Speed Sensor Malfunction
✅ C0040 – ABS Pump Motor Control Circuit
✅ C0110 – ABS System Failure
🧰 Body Codes (B-Codes)
✅ B0001 – Driver Airbag Deployment Circuit Fault
✅ B0020 – Passenger Airbag Circuit Malfunction
✅ B0100 – Seat Belt Pretensioner Fault
🌐 Network / Communication Codes (U-Codes)
✅ U0100 – Lost Communication with ECU
✅ U0121 – Lost Communication with ABS Module
✅ U0155 – Lost Communication with Instrument Cluster
What Causes OBD Error Codes?
✅ Faulty sensors
✅ Damaged wiring or loose connectors
✅ Vacuum leaks
✅ Engine misfires
✅ Transmission faults
✅ ECU or module communication issues
Can You Drive with an OBD Error Code?
✅ Minor sensor codes → Short driving may be possible
❌ Misfire, transmission, ABS, or airbag codes → Not safe
👉 Always confirm severity using a factory workshop manual.
Why Workshop Manuals Matter for OBD Diagnostics
An OBD scanner only shows the code — not the repair solution.
At ManualsBay.com, official manuals include:
✅ Manufacturer-approved troubleshooting steps
✅ Wiring diagrams & connector pinouts
✅ Sensor testing values
✅ Torque specifications
✅ Step-by-step repair procedures
This prevents wrong repairs and unnecessary part replacement.
Why Mechanics & DIY Users Trust ManualsBay.com
ManualsBay.com is a secure, global platform for professional repair documentation.
✅ OEM factory service manuals
✅ Instant PDF downloads
✅ Cars, motorcycles, ATVs & more
✅ Trusted by technicians worldwide
From OBD diagnostics to full engine rebuilds, ManualsBay provides accurate & reliable information.
Final Conclusion
OBD error codes are the language your vehicle uses to report problems. Understanding these codes helps you diagnose issues early, avoid costly repairs, and keep your vehicle safe.
For correct diagnostics and professional repair guidance, always rely on official workshop manuals from ManualsBay.com.
🔹 FAQ Schema Questions?
❓ What are OBD error codes?
OBD error codes are diagnostic trouble codes stored by a vehicle’s ECU to identify system faults.
❓ Are OBD-II codes universal?
Yes, generic OBD-II codes are standard worldwide, but manufacturer-specific codes vary by brand.
❓ Can an OBD scanner fix the problem?
No, scanners only read codes. Repairs require proper service manuals.
❓ Is it safe to clear OBD codes?
Clearing codes resets the warning light but does not fix the underlying issue.
❓ Where can I get official manuals to fix OBD codes?
You can download trusted OEM workshop manuals from ManualsBay.com.
