Navigating car troubles can be stressful, especially when the check engine light illuminates in your 1999 Honda Accord. Understanding OBD2 (On-Board Diagnostics II) codes is the first step to diagnosing and resolving these issues effectively. This guide provides a detailed look into OBD2 codes for your 1999 Honda Accord, helping you understand what these codes mean and how to approach troubleshooting.
Understanding OBD2 Systems in Your 1999 Honda Accord
The OBD2 system is a standardized system implemented in vehicles starting from 1996. It’s designed to monitor various components of your car, particularly those related to emissions, and alert you to potential problems through diagnostic trouble codes (DTCs). Before OBD2, manufacturers used proprietary systems, making it difficult for independent mechanics and car owners to diagnose issues. OBD2 brought uniformity, making vehicle diagnostics more accessible.
What Exactly is OBD2?
OBD2 is a set of standards that dictate the type of diagnostic connector, the communication protocols, and the range of diagnostic parameters available in vehicles. It’s a significant advancement from earlier systems, offering a standardized approach to vehicle diagnostics across different makes and models. Prior to OBD2, accessing diagnostic information often involved complex procedures and manufacturer-specific tools. OBD2 simplifies this process significantly.
Decoding OBD2 Codes
OBD2 codes are five-digit alphanumeric codes. Each character provides crucial information:
- First Character: Indicates the system where the fault occurred:
- P (Powertrain): Engine, transmission, and related components.
- B (Body): Body control systems like airbags, power windows, etc.
- C (Chassis): Chassis systems such as ABS, suspension, etc.
- U (Network): Communication network systems.
- Second Character: Indicates if the code is generic or manufacturer-specific:
- 0: Generic OBD2 code (standard across all manufacturers).
- 1: Manufacturer-specific code (unique to Honda in this case).
- Third Character: Specifies the subsystem:
- 0: Fuel and air metering and auxiliary emission controls.
- 1: Fuel and air metering.
- 2: Fuel and air metering (injector circuit).
- 3: Ignition system or misfires.
- 4: Auxiliary emission controls.
- 5: Vehicle speed controls and idle control system.
- 6: Computer output circuit.
- 7 & 8: Transmission.
- Last Two Characters: Indicate the specific fault within the subsystem.
For example, a code like P0117 breaks down as:
- P: Powertrain
- 0: Generic OBD2 code
- 1: Fuel and air metering
- 17: Specific fault number, in this case, “Engine Coolant Temperature Circuit Low Input”.
Accessing OBD2 Codes on Your 1999 Honda Accord
Contrary to a common misconception, you don’t always need a professional mechanic or a specialized OBD2 scan tool to retrieve codes from your 1999 Honda Accord. You can use a simple paperclip method to access basic codes, although for detailed diagnostics and clearing codes, an OBD2 scanner is highly recommended.
The Paperclip Method (for basic CEL codes):
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Locate the OBD2 connector: It’s typically found under the driver’s side dashboard.
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Prepare a paperclip: Straighten a paperclip into a U-shape.
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Insert the paperclip: As shown in the image, insert the paperclip into the specified pins of the OBD2 connector.
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Turn the ignition to the “ON” position (do not start the engine).
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Read the codes: The check engine light will blink in patterns. Long blinks represent ’10’ and short blinks represent ‘1’. Count the blinks to decipher the codes. For example, two long blinks followed by three short blinks would be code 23.
Using an OBD2 Scanner (Recommended for comprehensive diagnostics):
For more detailed information, including OBD2 codes (P-codes) and the ability to clear codes, using an OBD2 scanner is the best approach. These scanners are readily available online and at auto parts stores.
- Plug the scanner into the OBD2 port.
- Turn the ignition to the “ON” position.
- Follow the scanner’s instructions to read diagnostic codes.
- The scanner will display the codes and often provide descriptions.
Common 1999 Honda Accord OBD2 Codes
Here’s a compilation of OBD2 codes relevant to the 1999 Honda Accord, combining both OBD2 (P-codes) and the older CEL codes for your reference:
OBD2 Codes (P-Codes) and Corresponding CEL Codes for 1999 Honda Accord:
| MIL (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, P0715, P0720, P0725, P0730, P0740, P0753, P0758, P0763, P0780, P1660, P1705, P1706, P1738, P1739, P1753, P1758, P1768, P1773, P1785, P1786, P1790, P1791, P1792, P1793, P1794, P1870, P1873, P1879, P1885, P1886, P1888, P1890, P1891 | 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 |
Plain CEL Codes and Descriptions for 1999 Honda Accord:
| CODE | DEFINITION |
|---|---|
| 1 | Oxygen Sensor “A” (Primary) defective circuit or unplugged / defective sensor |
| 2 | Oxygen Sensor “B” defective circuit or unplugged / defective sensor |
| 3 | MAP Sensor (Manifold Absolute Pressure) defective circuit or unplugged / defective sensor |
| 4 | CKP Sensor (Crankshaft Position Sensor) defective circuit or unplugged / defective sensor |
| 5 | MAP Sensor (Manifold Absolute Pressure) mechanical problem / disconnected piping * not 94-95 |
| 6 | ECT Sensor (Engine Coolant Temperature) defective circuit or unplugged / defective sensor |
| 7 | TP Sensor (Throttle Position) defective circuit or unplugged / defective sensor |
| 8 | TDC Sensor (Top Dead Center) defective circuit or unplugged / defective sensor |
| 9 | CYP Sensor (Cylinder) defective circuit or unplugged / defective sensor * invalid code for throttle body injection Hondas ** invalid code for V6 engines |
| 10 | IAT Sensor (Intake Air Temperature) defective circuit or unplugged / defective sensor |
| 12 | EGR Lift Sensor (Exhaust Gas Recirculation) defective circuit or unplugged / defective sensor * invalid code for non-equipped EGR valve vehicles |
| 13 | BARO Sensor (Atmospheric Pressure) defective circuit or unplugged / defective sensor |
| 14 | IAC Valve (Idle Air Control) defective circuit or unplugged / defective sensor |
| 15 | Ignition Output Signal missing or defective ignition output signal |
| 16 | Fuel Injector System defective circuit or unplugged / defective fuel injector |
| 17 | VSS (Vehicle Speed Sensor) defective circuit or unplugged / defective sensor |
| 19 | Automatic Transmission Lock Up Control Solenoid Valve defective circuit or unplugged / defective solenoid valve |
| 20 | Electrical Load Detector defective circuit or unplugged / defective sensor |
| 21 | VTEC Solenoid Valve defective circuit or unplugged / defective solenoid valve * invalid code for non-VTEC engine ** invalid for V6 engine |
| 22 | VTEC Oil Pressure Switch defective circuit or unplugged / defective oil pressure switch * invalid code for non-VTEC engine |
| 23 | KS (Knock Sensor) defective circuit or unplugged / defective sensor * invalid code for V6 engine |
| 30 | Automatic Transmission Signal: “A” / SEAF / SEFA / TMA or TMB defective circuit or unplugged / defective sensor * invalid code for 1996 |
| 31 | Automatic Transmission Signal “B” defective circuit or unplugged / defective sensor |
| 41 | Primary Oxygen Sensor – Heater circuit malfunction |
| 43 | Fuel Supply System defective or malfunctioning fuel supply system |
| 45 | System Too Lean or Too Rich malfunction in the fuel monitoring systems |
| 48 | LAF Sensor (Lean Air Fuel) defective circuit or unplugged / defective sensor |
| 54 | CKF Sensor (Crankshaft Speed Fluctuation) defective circuit or unplugged / defective sensor |
| 61 | Oxygen Sensor, Heated – Sensor 1 (Primary) high voltage, low voltage, or slow response |
| 63 | Oxygen Sensor, Heated – Sensor 2 (Secondary) high voltage, low voltage, or slow response |
| 65 | Oxygen Sensor Heater (Secondary) malfunctioning or defective oxygen sensor heater |
| 67 | Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system |
| 70 | Automatic Transmission malfunction with the automatic transmission controls |
| 71 | Cylinder 1 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire |
| 72 | Cylinder 2 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire |
| 73 | Cylinder 3 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire |
| 74 | Cylinder 4 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire |
| 80 | Exhaust Gas Recirculation insufficient flow detected |
| 86 | ECT Sensor (Engine Coolant Temperature) circuit range / performance problem |
| 90 | Evaporative Emission Control System leak detected in the fuel tank area |
| 91 | Fuel Tank Pressure Sensor low input |
| 92 | Evaporative Emission Control System insufficient purge flow |
Note: This list is not exhaustive, but it covers the most common OBD2 and CEL codes you might encounter in a 1999 Honda Accord.
Troubleshooting and Next Steps
Once you have retrieved the OBD2 code from your 1999 Honda Accord, you should:
- Research the Code: Use the provided tables and online resources like obd-codes.com to understand the potential issue indicated by the code.
- Visual Inspection: Check for obvious problems like loose gas caps, disconnected sensors, or damaged wiring related to the indicated system.
- Consult a Professional: While some issues might be simple fixes, many OBD2 codes point to complex problems that require professional diagnostic equipment and expertise.
Understanding OBD2 codes is empowering, but accurate diagnosis and repair often require the skills of a certified mechanic. If you’re unsure about how to proceed, especially with more complex codes or persistent issues, it’s always wise to seek professional help. Websites like cardiagnosticnearme.com can assist you in finding qualified auto repair professionals in your vicinity to accurately diagnose and fix your 1999 Honda Accord’s OBD2 code issues.
