The dreaded check engine light (CEL) – or malfunction indicator light (MIL) – illuminating on your Honda dashboard can be a stressful experience. Diagnostic trouble codes (DTCs) are the key to understanding what your car is trying to tell you. While modern vehicles are equipped with OBD-II systems readable by scanners, many Honda owners are unaware that they can access these codes without any special tools, using the simple “blink code” method. This guide will empower you to understand Honda Obd2 Blink Codes, diagnose common issues, and take the first steps towards resolving them, all from the comfort of your garage.
Understanding OBD-II and Honda Blink Codes
Before the standardization of On-Board Diagnostics II (OBD-II) in the mid-1990s, automotive diagnostics were far less uniform. Each manufacturer often had its own proprietary systems for accessing trouble codes. Early systems, including those in Hondas, relied on blink codes. These codes were communicated by the check engine light flashing in patterns, a sort of automotive Morse code.
OBD-II changed the game by standardizing diagnostic protocols across virtually all car manufacturers sold in the United States from 1996 onwards. This standardization included a universal diagnostic connector, a set of standardized DTCs, and communication protocols. While OBD-II scanners became the primary tool for reading these codes, Honda retained the blink code system as a supplementary, tool-free method for accessing basic diagnostic information.
For Honda owners, this is incredibly useful. It means you don’t always need to rush to an auto parts store or mechanic to understand why your check engine light is on. You can quickly retrieve blink codes and get a general idea of the problem, allowing you to make informed decisions about repair or further diagnosis.
How to Retrieve Honda OBD2 Blink Codes: The Paperclip Method
Retrieving Honda OBD2 blink codes is surprisingly straightforward and requires only a simple paperclip. Here’s a step-by-step guide:
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Locate the OBD-II Connector: In most Honda vehicles manufactured from the mid-1990s onwards, the OBD-II data link connector is located under the driver’s side dashboard. It’s typically near the steering column and looks like a trapezoidal, 16-pin port.
Alt Text: Location of the OBD2 diagnostic port under the dashboard of a Honda vehicle, driver’s side.
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Prepare Your Paperclip: Take a standard paperclip and bend it into a U-shape. You’ll be using this to bridge two specific terminals in the OBD-II connector.
Alt Text: A paperclip bent into a U-shape, prepared for use in bridging terminals on a Honda OBD2 connector for blink code reading.
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Insert the Paperclip: Identify the two terminals to bridge. These are typically terminals 4 and 9 on many Honda models, but it’s always best to consult your Honda service manual or reliable online resources specific to your model year to confirm the correct terminals. Carefully insert each end of the paperclip into the designated terminals on the OBD-II connector. Ensure the ignition is off when doing this.
Alt Text: Close-up view of a paperclip correctly inserted into the OBD2 connector of a Honda, bridging two terminals to initiate blink code readout.
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Turn the Ignition to “ON” (Do Not Start Engine): Turn your ignition key to the “ON” position, but do not start the engine.
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Observe the Check Engine Light: Watch the check engine light on your dashboard. It will begin to blink in a pattern. The blink codes are typically two-digit numbers. Long blinks represent the tens digit, and short blinks represent the ones digit. For example, one long blink followed by three short blinks indicates code 13. There will be a slightly longer pause between codes if multiple codes are stored.
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Record the Codes: Carefully count and record the blink codes. Repeat the process a few times to ensure you have correctly identified all stored codes.
Understanding Honda OBD2 Codes and Their Meanings
Once you have retrieved the blink codes, you need to decipher their meaning. Honda OBD2 codes, like all OBD-II codes, follow a standardized format. However, Honda blink codes are a simplified representation of these OBD-II codes, often corresponding to the older, pre-OBD-II Honda specific codes.
Here’s a breakdown of common Honda OBD2 blink codes and their potential meanings:
Honda CEL Codes (Blink Codes) to OBDII Code Cross-Reference:
| CEL Code | OBDII Code | Description of Code |
|---|---|---|
| 1 | P0131 | Primary HO2S Circuit Low Voltage (Sensor 1) |
| 1 | P0132 | Primary HO2S Circuit High Voltage (Sensor 1) |
| 3 | P0107 | MAP Circuit Low Input |
| 3 | P0108 | MAP Circuit High Input |
| 4 | P0335 | CKP Sensor Circuit Low Input |
| 4 | P0336 | CKP Sensor Range/Performance |
| 5 | P0106 | MAP Circuit Range Or Performance |
| 5 | P1128 | MAP Lower Than Expected |
| 5 | P1129 | MAP Higher Than Expected |
| 6 | P0117 | ECT Circuit Low Input |
| 6 | P0118 | ECT Circuit High Input |
| 7 | P0122 | TP Sensor Circuit Low Input |
| 7 | P0123 | TP Sensor Circuit High Input |
| 7 | P1121 | Throttle Position Lower Than Expected |
| 7 | P1122 | Throttle Position Higher Than Expected |
| 8 | P1359 | CKP/TDC Sensor Connector Disconnection |
| 8 | P1361 | TDC Sensor Intermittent Interruption |
| 8 | P1362 | TDC Sensor No Signal |
| 9 | P1381 | Cylinder Position Sensor Intermittent Interruption |
| 9 | P1382 | Cylinder Position Sensor No Signal |
| 10 | P0111 | IAT Sensor Circuit Range/Performance |
| 10 | P0112 | IAT Sensor Circuit Low Input |
| 10 | P0113 | IAT Sensor Circuit High Input |
| 12 | P1491 | EGR Valve Lift Insufficient Detected |
| 12 | P1498 | EGR Valve Lift Sensor High Voltage |
| 13 | P1106 | BARO Circuit Range/Performance |
| 13 | P1107 | BARO Circuit Low Input |
| 13 | P1108 | BARO Circuit High Input |
| 14 | P0505 | ICS Malfunction |
| 14 | P1508 | IAC Valve Circuit Failure |
| 14 | P1509 | IAC Valve Circuit Failure |
| 14 | P1519 | Idle Air Control Valve Circuit Failure |
| 17 | P0500 | VSS Circuit Malfunction (M/T) |
| 17 | P0501 | VSS Circuit Range/Performance (A/T) |
| 20 | P1297 | Electrical Load Detector Circuit Low Input |
| 20 | P1298 | Electrical Load Detector Circuit High Input |
| 21 | P1253 | VTEC System Malfunction |
| 22 | P1257, P1258, P1259 | VTEC System Malfunction |
| 23 | P0325 | KS Circuit Malfunction |
| 30 | P1655 | SEAF/SEFA/TMA/TMB Signal Line Failure |
| 30 | P1681 | A/T FI Signal A Low Input |
| 30 | P1682 | A/T FI Signal A High Input |
| 31 | P1686 | A/T FI Signal B Low Input |
| 31 | P1687 | A/T FI Signal B High Input |
| 34 | P0560 | Powertrain Control Module (PCM) Backup Voltage Circuit Low Voltage |
| 41 | P0135 | Front HO2S Heater Circuit Fault (Sensor 1) |
| 41 | P1166 | Primary HO2S (No. 1) Heater System Electrical |
| 41 | P1167 | Primary HO2S (No. 1) Heater System |
| 45 | P0171 | System Too Lean |
| 45 | P0172 | System Too Rich |
| 48 | P1162 | Primary HO2S (No. 1) Circuit Malfunction |
| 48 | P1168 | Primary HO2S (No. 1) LABEL Low Input |
| 48 | P1169 | Primary HO2S (No. 1) LABEL High Input |
| 54 | P1336 | CSF Sensor Intermittent Interruption |
| 54 | P1337 | CSF Sensor No Signal |
| 58 | P1366 | TDC Sensor No. 2 Intermittent Interruption |
| 58 | P1367 | TDC Sensor No 2 Signal |
| 61 | P0133 | Primary HO2S Circuit Slow Response (Sensor 1) |
| 61 | P1149 | Primary HO2S (Sensor 1) Circuit Range/Performance Problem |
| 61 | P1163 | Primary HO2S (No. 1) Circuit Slow Response |
| 61 | P1164 | Primary HO2S (No. 1) Circuit Range/Performance |
| 61 | P1165 | Primary HO2S (No. 1) Circuit Range/Performance |
| 63 | P0137 | Secondary HO2S Circuit Low Voltage (Sensor 2) |
| 63 | P0138 | Secondary HO2S Circuit High Voltage (Sensor 2) |
| 63 | P0139 | Secondary HO2S Circuit Slow Response (Sensor 2) |
| 65 | P0141 | Secondary HO2S Heater Circuit Fault (Sensor 2) |
| 67 | P0420 | Catalyst System Efficiency Below Threshold |
| 70 | P0700, etc. | A/T Concerns |
| 70 | P1660 | A/T FI Signal A Circuit Failure |
| 70 | P1705, etc. | A/T Concerns |
| 70 | P1870, etc. | A/T Concerns |
| 71 | P0301 | Misfire Cyl. 1 Or Random Misfire |
| 72 | P0302 | Misfire Cyl. 2 Or Random Misfire |
| 73 | P0303 | Misfire Cyl. 3 Or Random Misfire |
| 74 | P0304 | Misfire Cyl. 4 Or Random Misfire |
| 75 | P0305 | Misfire Cyl. 5 Or Random Misfire |
| 76 | P0306 | Misfire Cyl. 6 Or Random Misfire |
| 80 | P0401 | EGR Insufficient Flow Detected |
| 86 | P0116 | ECT Circuit Range Or Performance |
| 90 | P1456 | EVAP Emission Control System Leak Detected (Fuel Tank System) |
| 90 | P1457 | EVAP Emission Control System Leak Detected (Control Canister System) |
| 91 | P0451 | Fuel Tank Pressure Sensor Range/Performance |
| 91 | P0452 | Fuel Tank Pressure Sensor Circuit Low Input |
| 91 | P0453 | Fuel Tank Pressure Sensor Circuit High Input |
| 92 | P0441 | EVAP Emission Control System Improper Purge Flow |
| 92 | P1459 | EVAP Emission Purge Flow Switch Malfunction |
| — | P0300 | Random Misfire |
| — | P1486 | Thermostat Range/Performance Problem |
| — | P1607 | ECM/PCM Internal Circuit Failure A |
| — | P1676 | FPTDR Signal Line Failure |
| — | P1678 | FPTDR Signal Line Failure |
| 71-74 | P1300 | Multiple Cylinder Misfire Detected |
Note: “HO2S” refers to Heated Oxygen Sensor, “MAP” is Manifold Absolute Pressure, “ECT” is Engine Coolant Temperature, “TP” is Throttle Position, “CKP” is Crankshaft Position, “TDC” is Top Dead Center, “IAT” is Intake Air Temperature, “EGR” is Exhaust Gas Recirculation, “BARO” is Barometric Pressure, “ICS” is Idle Control System, “VSS” is Vehicle Speed Sensor, “VTEC” is Variable Valve Timing and Lift Electronic Control, “KS” is Knock Sensor, “CSF” is Crankshaft Speed Fluctuation, “EVAP” is Evaporative Emission Control System, “A/T” is Automatic Transmission.
This table provides a starting point for diagnosis. For example, a code 7 (P0122 or P0123) points to a Throttle Position Sensor issue. This could be due to a faulty sensor, wiring problems, or even throttle body issues. Similarly, codes in the 40s (like 41, 45, 48) often relate to oxygen sensor or fuel mixture problems.
Limp Mode and Honda OBD2 Codes
OBD-II systems include “limp home” or “limp mode,” a safety feature designed to protect the engine and allow you to drive the car to a safe location or repair shop when a critical fault occurs. Certain sensor failures, as indicated by OBD2 codes, can trigger limp mode. In limp mode, the Engine Control Module (ECM) restricts engine power and performance to prevent further damage.
Sensors that can trigger limp mode in Hondas, often indicated by specific OBD2 codes, include:
- Mass Air Flow (MAF) / Manifold Absolute Pressure (MAP) Sensor (P0100, P0105, P0106, P0107, P0108, P1128, P1129): These sensors are crucial for measuring air intake. Failure can lead to incorrect fuel delivery.
- Intake Air Temperature (IAT) Sensor (P0110, P0111, P0112, P0113): Inaccurate air temperature readings affect fuel mixture calculations.
- Throttle Position Sensor (TPS) (P0120, P0122, P0123, P1121, P1122): Essential for determining engine load and acceleration.
- Engine Coolant Temperature (ECT) Sensor (P0115, P0116, P0117, P0118, P0119, P011A, P011B): Critical for engine temperature management and fuel control.
- Camshaft Position (CMP) Sensor (P0340, P0341, P0342, P0343, P0344, P0345, P0346, P0347, P0348, P0349): Used for precise ignition and fuel injection timing.
- Crankshaft Position (CKP) Sensor (P0335, P0336, P0337, P0338, P0339): Provides essential engine speed and position data.
If your Honda enters limp mode, retrieving the blink codes can help you pinpoint the problematic sensor and system.
Beyond Blink Codes: When to Use an OBD2 Scanner
While Honda blink codes are a valuable tool for initial diagnosis, they have limitations. Blink codes provide only a basic two-digit code, which is a simplified version of the more detailed OBD-II DTC. For in-depth diagnostics, especially with modern Hondas, an OBD2 scanner is highly recommended.
OBD2 scanners offer several advantages:
- Detailed OBD-II DTCs: Scanners display the full five-digit OBD-II code (e.g., P0131), providing more specific information.
- Code Definitions: Scanners typically provide a text description of the code, eliminating the need to look up codes manually.
- Live Data: Scanners can display real-time sensor data, allowing you to monitor engine parameters and identify intermittent faults.
- Enhanced Diagnostics: Many scanners offer advanced functions like freeze frame data (snapshot of sensor readings when the code was set), and the ability to clear codes after repairs.
For serious DIYers or anyone wanting a more comprehensive understanding of their Honda’s health, investing in a quality OBD2 scanner is a worthwhile step.
Conclusion
Honda OBD2 blink codes are a fantastic, tool-free resource for initial diagnostics. By understanding how to retrieve and interpret these codes, you can gain valuable insights into your vehicle’s issues and make informed decisions about maintenance and repair. While blink codes offer a starting point, remember that modern OBD2 scanners provide more detailed information and advanced diagnostic capabilities. Whether you are a seasoned mechanic or a new Honda owner, mastering Honda OBD2 blink codes is a valuable skill that can save you time and money, and keep your Honda running smoothly.
