Understanding the OBD2 (On-Board Diagnostics II) system in your Honda is crucial for effective vehicle maintenance and repair. This standardized system allows you to access a wealth of information about your car’s health, performance, and potential issues. At the heart of this system is the OBD2 port, a standardized connector that provides access to your vehicle’s computer. Knowing the Honda OBD2 pinout is the first step in utilizing diagnostic tools and understanding communication protocols.
Honda OBD2 Pinout Diagram
The OBD2 port in your Honda, like most modern vehicles, is a 16-pin connector. Here’s a breakdown of the standard Honda OBD2 pinout, which is consistent with the generic OBD2 standard while having specific Honda-related applications for some pins:
| Pin | Signal | Description |
|---|---|---|
| 1 | Manufacturer Discretionary | Often unused or manufacturer-specific |
| 2 | SAE J1850 Bus+ | Positive line for J1850 PWM & VPW protocols (Ford SCP) |
| 3 | Manufacturer Discretionary | Often unused or manufacturer-specific |
| 4 | CGND | Chassis Ground |
| 5 | SGND | Signal Ground |
| 6 | CAN High | CAN bus high (J-2284) |
| 7 | K-Line | ISO 9141-2 and ISO/DIS 14230-4 (KWP2000) |
| 8 | Manufacturer Discretionary | Often unused or manufacturer-specific |
| 9 | SCS | Service Check System (Honda Specific Diagnostic) |
| 10 | SAE J1850 Bus- | Negative line for J1850 PWM & VPW protocols (Ford SCP) |
| 11 | Manufacturer Discretionary | Often unused or manufacturer-specific |
| 12 | Programming Out | Used for ECU programming (Manufacturer Specific) |
| 13 | Manufacturer Discretionary or VTM-4/Immobilizer | VTM-4 and Immobilizer control Input/Output (Potentially) |
| 14 | CAN Low | CAN bus low (J-2284) |
| 15 | ISO 9141-2 L-Line | ISO 9141-2 and ISO/DIS 14230-4 (KWP2000) |
| 16 | +12V | Battery Power (Unswitched) |
Understanding Key Pins in Honda OBD2
- Pin 4 & 5 (Grounds): These pins provide the necessary ground connections for the OBD2 interface to function correctly. Pin 4 is Chassis Ground, while Pin 5 is Signal Ground, ensuring stable electrical reference.
- Pin 6 & 14 (CAN Bus): CAN (Controller Area Network) bus is a high-speed communication protocol widely used in modern vehicles. Pins 6 (CAN High) and 14 (CAN Low) are essential for vehicles using CAN protocols, which became prevalent in Honda vehicles from around 2006-2008 onwards.
- Pin 7 & 15 (K-Line & L-Line): These pins are used for the ISO 9141-2 and ISO 14230-4 (KWP2000) protocols, common in older OBD2 compliant Honda models (roughly pre-2006). K-Line (Pin 7) is the primary communication line, while L-Line (Pin 15) is sometimes used for wake-up or specific functions.
- Pin 9 (SCS): This pin is particularly interesting for Honda owners. SCS stands for Service Check System. In some older Honda models, bridging this pin to ground can initiate diagnostic mode or retrieve basic diagnostic codes directly from the vehicle’s ECU without an external OBD2 scanner. This is a Honda-specific feature and not part of the generic OBD2 standard for all manufacturers.
- Pin 16 (+12V Battery Power): This pin provides the OBD2 diagnostic tool with power directly from the car battery, even when the ignition is off. This ensures the tool can communicate with the vehicle’s systems.
Honda OBD2 Compatibility and Protocols
Honda vehicles, like all cars sold in the US from 1996 onwards, are OBD2 compliant. However, the specific communication protocols used have evolved over the years. Here’s a general guide to Honda OBD2 compatibility and the protocols they typically employ:
| Model | Engine | Year (starting from) | OBD-2 Protocol |
|---|---|---|---|
| Honda Accord | 1998 | ISO 14230-4, ISO 9141-2 | |
| 2.0 iES, Gasoline (147HP) | 1998 | ISO 9141 | |
| 2000 | ISO 14230-4, ISO 9141-2 | ||
| 2.2 CTDI, Diesel (139 HP) | 2005 | ISO 9141-2 | |
| Gasoline (188 HP) | 2006 | ||
| Honda Accord Coupe | Gasoline (198 HP) | 2001 | ISO 9141-2 |
| Honda CITY TYPE Z | Gasoline (155 HP) | 1999 | – |
| Honda Civic | 1996 | ISO 14230-4, ISO 9141-2 | |
| 2000 | ISO 14230-4, ISO 9141-2 | ||
| 1.4 IS, Gasoline (90HP) | 2000 | ISO 9141 | |
| 2001 | ISO 14230-4, ISO 9141-2 | ||
| Diesel (100 HP) | 2003 | ISO 14230-4, ISO 9141-2 | |
| 1.7 mfi, Gasoline (115HP) | 2003 | ISO 9141 | |
| 2, Gasoline (200HP) | 2003 | ISO 9141 | |
| 1.7 CTDI, Diesel (100HP) | 2004 | ISO 9141 | |
| 2.0 16V, Gasoline (200HP) | 2005 | ISO 9141 | |
| Gasoline (112 HP) | 2006 | ||
| 1.4 I-DSI, Gasoline (83HP) | 2006 | CAN 29bit | |
| 1.8, Gasoline (140HP) | 2006 | CAN 29bit | |
| 2.2 i-CtdI, Diesel (140HP) | 2006 | CAN 29bit | |
| 1.8, Gasoline (140HP) | 2009 | CAN 29bit | |
| Honda civic coupe em2 | Gasoline (120 HP) | 2001 | ISO 9141-2 |
| Honda Civic Del Sol | 1997 | ISO 14230-4, ISO 9141-2 | |
| Honda Civic EV1 | Gasoline (159 HP) | 2005 | ISO 9141-2 |
| Honda Civic Type R | 2003 | ISO 14230-4, ISO 9141-2 | |
| Honda Civic TypeR-FN2 | Gasoline (199 HP) | 2007 | ISO 9141-2 |
| Honda CR-V | Diesel (139 HP) | 2006 | |
| 2.2 CDTI, Diesel (140HP) | 2005 | ISO 9141 | |
| Gasoline (148 HP) | 2002 | ISO 9141-2 | |
| Diesel (148 HP) | 2010 | ISO 9141-2 | |
| Honda CR-Z | 1.5, Hyb (124HP) | 2010 | CAN 29bit |
| Honda Fit | 1.2, Gasoline (65HP) | 2003 | ISO 9141 |
| Honda FR-V | 2.2 CDTI, Diesel (140HP) | 2006 | ISO 9141 |
| Honda HR-V | 1.6, Gasoline (124HP) | 2001 | ISO 9141 |
| Honda Jazz | 1.2, Gasoline (80HP) | 2002 | ISO 9141 |
| 1.4, Gasoline (82 HP) | 2003 | ||
| 1.2, Gasoline (65HP) | 2003 | ISO 9141 | |
| 1.2, Gasoline (104 HP) | 2004 | ||
| 1.4 i-dsi cvt, Gasoline (83HP) | 2005 | ISO 9141 | |
| Honda Legend | Gasoline (171 HP) | 1990 | – |
| 3.5 VTEC, Gasoline (295HP) | 2006 | ISO 9141 | |
| Honda Odyssey | 2002 | ISO 14230-4, ISO 9141-2 | |
| Honda rd8 | Gasoline (149 HP) | 2002 | – |
| Honda S2000 | 2.0 dohc 16s, Gasoline (240HP) | 2002 | ISO 9141 |
| 2000 | ISO 14230-4, ISO 9141-2 | ||
| Gasoline (238 HP) | 2006 | ||
| Honda Stream 2.0 | Gasoline (155 HP) | 2004 | |
| Honda TYPE R | Gasoline (249 HP) | 2005 |
General Honda OBD2 Protocol Timeline:
- 1996 – 2006: Primarily ISO 9141 protocol.
- 2006 – 2008: Transition period, may use ISO 9141 or CAN protocols.
- 2008 and later: Predominantly CAN (likely CAN 29bit as indicated in the table).
Note: This compatibility list is not exhaustive. Always refer to your vehicle’s repair manual or manufacturer specifications for definitive OBD2 protocol information.
Decoding Honda OBD-II Diagnostic Trouble Codes (DTCs)
OBD2 systems use standardized Diagnostic Trouble Codes (DTCs) to indicate detected issues. These codes are five-character alphanumeric codes. While generic OBD2 codes are standardized across manufacturers, some codes are manufacturer-specific. Here are some common Honda specific OBD-II diagnostic codes:
| Code | Description |
|---|---|
| P1106 | Barometric Pressure Circuit Range/Performance |
| P1107 | Barometric Pressure Circuit Low Input |
| P1108 | Barometric Pressure Circuit High Input |
| P1121 | Throttle Position Lower Than Expected |
| P1122 | Throttle Position Higher Than Expected |
| P1128 | MAP Lower Than Expected |
| P1129 | MAP Higher Than Expected |
| P1149 | Primary HO2S (Sensor 1) Circuit Range/Performance Problem |
| P1162 | Primary HO2S (No. 1) Circuit Malfunction |
| P1163 | Primary HO2S (No. 1) Circuit Slow Response |
| P1164 | Primary HO2S (No. 1) Circuit Range/Performance |
| P1165 | Primary HO2S (No. 1) Circuit Range/Performance |
| P1166 | Primary HO2S (No. 1) Heater System Electrical |
| P1167 | Primary HO2S (No. 1) Heater System |
| P1168 | Primary HO2S (No. 1) LABEL Low Input |
| P1169 | Primary HO2S (No. 1) LABEL High Input |
| P1253 | VTEC System Malfunction |
| P1257 | VTEC System Malfunction |
| P1258 | VTEC System Malfunction |
| P1259 | VTEC System Malfunction |
| P1297 | Electrical Load Detector Circuit Low Input |
| P1298 | Electrical Load Detector Circuit High Input |
| P1300 | Multiple Cylinder Misfire Detected |
| P1336 | CSF Sensor Intermittent Interruption |
| P1337 | CSF Sensor No Signal |
| P1359 | CKP/TDC Sensor Connector Disconnection |
| P1361 | Intermittent Interruption In TDC 1 Sensor Circuit |
| P1362 | No Signal In TDC 1 Sensor Circuit |
| P1366 | Intermittent Interruption In TDC 2 Sensor Circuit |
| P1367 | No Signal In TDC 2 Sensor Circuit |
| P1381 | Cylinder Position Sensor Intermittent Interruption |
| P1382 | Cylinder Position Sensor No Signal |
| P1456 | EVAP Emission Control System Leak Detected (Fuel Tank System) |
| P1457 | EVAP Emission Control System Leak Detected (Control Canister System) |
| P1459 | EVAP Emission Purge Flow Switch Malfunction |
| P1486 | Thermostat Range/Performance Problem |
| P1491 | EGR Valve Lift Insufficient Detected |
| P1498 | EGR Valve Lift Sensor High Voltage |
| P1508 | IAC Valve Circuit Failure |
| P1509 | IAC Valve Circuit Failure |
| P1519 | Idle Air Control Valve Circuit Failure |
| P1607 | ECM/PCM Internal Circuit Failure A |
| P1655 | SEAF/SEFA/TMA/TMB Signal Line Failure |
| P1656 | Automatic Transaxle |
| P1660 | Automatic Transaxle FI Signal A Circuit Failure |
| P1676 | FPTDR Signal Line Failure |
| P1678 | FPTDR Signal Line Failure |
| P1681 | Automatic Transaxle FI Signal A Low Input |
| P1682 | Automatic Transaxle FI Signal A High Input |
| P1686 | Automatic Transaxle FI Signal B Low Input |
| P1687 | Automatic Transaxle FI Signal B High Input |
| P1705 | Automatic Transaxle Concerns |
| P1706 | Automatic Transaxle Concerns |
| P1738 | Automatic Transaxle Concerns |
| P1739 | Automatic Transaxle Concerns |
| P1753 | Automatic Transaxle Concerns |
| P1758 | Automatic Transaxle Concerns |
| P1768 | Automatic Transaxle Concerns |
| P1773 | Automatic Transaxle Concerns |
| P1785 | Automatic Transaxle Concerns |
| P1786 | Automatic Transaxle Concerns |
| P1790 | Automatic Transaxle Concerns |
| P1791 | Automatic Transaxle Concerns |
| P1792 | Automatic Transaxle Concerns |
| P1793 | Automatic Transaxle Concerns |
| P1794 | Automatic Transaxle Concerns |
| P1870 | Automatic Transaxle Concerns |
| P1873 | Automatic Transaxle Concerns |
| P1879 | Automatic Transaxle Concerns |
| P1885 | Automatic Transaxle Concerns |
| P1886 | Automatic Transaxle Concerns |
| P1888 | Automatic Transaxle Concerns |
| P1890 | Automatic Transaxle Concerns |
| P1891 | Automatic Transaxle Concerns |
Note: “Automatic Transaxle Concerns” is a very generic description and often requires further diagnosis with Honda specific tools to pinpoint the exact issue within the automatic transmission system.
Further Resources and OBD-II Cable Schematics
To effectively use your Honda OBD2 port, you might need specific cables and diagnostic tools. Here are some resources for OBD-II cable schematics that are relevant to different protocols used in Honda vehicles:
- OBD-2 ISO 9141-2 (14230-4, KWP2000) simple serial cable
- OBD-2 J1850 PWM, J1850 VPW serial ELM327 cable
- OBD-2 universal ISO 15765-4 CAN, SAE J1850 PWM, SAE J1850 VPW, ISO 9141-2, ISO 14230-4 and SAE J1939 diagnostic cable
These links provide pinout diagrams for creating your own OBD2 cables or understanding the wiring of commercial cables, depending on the communication protocol your Honda uses.
By understanding your Honda OBD2 pinout, compatibility, and diagnostic codes, you are better equipped to diagnose and maintain your vehicle, potentially saving time and money on repairs. Remember to always consult your vehicle’s service manual for the most accurate and detailed information.
