Ensuring your 8th generation Honda Civic passes emissions testing, often referred to as DEQ (Department of Environmental Quality) testing in many regions, is crucial for legal roadworthiness. A key aspect of this process involves understanding and managing your vehicle’s OBD2 readiness codes. These codes are indicators of your car’s emission control systems’ self-testing status. This guide will delve into the specifics of OBD2 readiness codes for your 8th gen Civic, explaining what they are, how to check them, and how to ensure they are properly set for a successful DEQ test.
Understanding OBD2 Readiness Codes in Your 8th Gen Civic
OBD2 (On-Board Diagnostics II) systems are designed to monitor your vehicle’s emissions systems. Readiness codes, also known as readiness monitors, are a part of this system. They essentially report whether your Civic’s emission control systems have completed their self-tests. These tests are performed automatically by the car’s computer (ECM/PCM) under specific driving conditions.
When your Honda Civic’s battery is disconnected, goes flat, DTCs (Diagnostic Trouble Codes) are cleared, or the ECM/PCM is reset, these readiness codes are also reset to an “incomplete” state. For emissions testing, especially DEQ, most states require these codes to be in a “complete” or “ready” state. If they are not, your 8th gen Civic might fail the emissions test, or the test cannot be properly conducted.
Alt text: An OBD2 scanner tool is connected to the diagnostic port of a vehicle, used for checking car system status.
Checking 8th Gen Civic Readiness Codes: Two Methods
There are two primary methods to check the readiness code status on your 8th generation Civic: using the Malfunction Indicator Lamp (MIL) and using a diagnostic tool like the Honda Diagnostic System (HDS).
1. Using the Malfunction Indicator Lamp (MIL)
This is a quick visual check you can perform without any special tools:
- Turn the ignition switch to the ON (II) position – Do not start the engine.
- Observe the MIL (Check Engine Light) – The MIL will illuminate for approximately 15-20 seconds.
- Interpret the MIL behavior:
- MIL goes off after 15-20 seconds: This indicates that all readiness codes are set to “complete”.
- MIL flashes five times: This signifies that one or more readiness codes are “not set to complete” or “incomplete”.
This MIL method provides a general overview. For detailed information on specific readiness monitors, using a diagnostic tool is necessary.
2. Using a Diagnostic Tool (HDS or equivalent OBD2 Scanner)
For a comprehensive check, especially to identify which specific readiness codes are incomplete, using an OBD2 scanner or the Honda Diagnostic System (HDS) is recommended.
- Connect your OBD2 scanner to the data link connector (DLC) in your 8th gen Civic. This port is usually located under the dashboard on the driver’s side.
- Navigate to the DTC MENU on your scanner.
- Select OBD Status or Readiness Codes (the exact menu name may vary depending on your scanner).
- Review the Readiness Status: The scanner will display the status of each readiness monitor. It will show whether each monitor is “Complete” or “Incomplete”. It may also show related DTCs if any issues are preventing a monitor from completing.
Alt text: Screenshot of Honda Diagnostic System (HDS) software interface displaying vehicle diagnostic data.
Using a tool like HDS provides more in-depth information, including the enable criteria for each monitor and any temporary DTCs that might be hindering the readiness process.
Setting Readiness Codes on Your 8th Gen Civic: Step-by-Step Procedures
If your 8th gen Civic has incomplete readiness codes, you will need to perform specific drive cycles to allow the vehicle to run its self-tests and set the codes to “complete”. Below are the procedures for setting common readiness codes, as detailed for the 8th generation Honda Civic. Remember, do not turn off the ignition switch during these procedures unless specifically instructed. Also, keep in mind that all readiness codes are cleared when the battery is disconnected or the ECM/PCM is reset.
Factors Affecting Readiness Code Completion:
- Low Ambient Temperatures or Stop-and-Go Traffic: These conditions can extend the drive time required to set readiness codes.
- Enable Criteria: Each monitor has specific “enable criteria” (temperature, speed, etc.) that must be met for the test to run.
- Faults in Emission Systems: If there’s an underlying issue, like a faulty sensor, a readiness code might not set until the fault is corrected.
1. Catalytic Converter Monitor and Readiness Code
Enable Criteria:
- Engine Coolant Temperature (ECT) at 158 ºF (70 ºC) or more.
- Intake Air Temperature (IAT) at -13 ºF (-25 ºC) or more.
- Vehicle Speed Sensor (VSS) reading more than 3 mph (5 km/h).
Procedure:
- Connect HDS to the DLC and access the READINESS CODEs screen for Catalyst in the DTCs MENU.
- Start the engine.
- Test-drive: Drive under stop-and-go conditions with short periods of steady cruising for approximately 5 miles (8 km).
- Check Readiness: Re-check the readiness code status using HDS. It should now be “completed”.
- If Still Incomplete: Check for Temporary DTCs with HDS. If no DTCs are present, repeat the procedure, ensuring all enable criteria are met.
Alt text: Image showing the undercarriage of a car with the catalytic converter highlighted.
2. Evaporative Emission (EVAP) Control System Monitor and Readiness Code
Enable Criteria:
- Battery voltage more than 10.5 V.
- Engine at idle.
- ECT sensor between 176 ºF (80 ºC) and 212 ºF (100 ºC).
- MAP sensor less than 46.6 kPa (14 in.Hg, 350 mmHg).
- Vehicle speed 0 mph (0 km/h).
- IAT sensor between 32 ºF (0 ºC) and 212 ºF (100 ºC).
Procedure:
- Connect HDS to the DLC.
- Start the engine.
- EVAP Test: In HDS, go to INSPECTION MENU, select EVAP TEST, then FUNCTION TEST in the EVAP TEST MENU.
- Check Readiness: If the functions are normal according to HDS, readiness is complete.
- If Still Incomplete: Check for temporary DTCs. If no DTCs, repeat the procedure ensuring all enable criteria are met.
Alt text: Diagram illustrating components of an automotive Evaporative Emission (EVAP) control system.
3. Air Fuel Ratio (A/F) Sensor Monitor and Readiness Code
Enable Criteria:
- ECT at 158 ºF (70 ºC) or more.
Procedure:
- Start the engine.
- Test-drive: Drive under stop-and-go conditions with short periods of steady cruise for about 3.5 miles (5.6 km). During the drive, decelerate with the throttle fully closed for 5 seconds.
- Check Readiness: Use HDS to check the readiness codes screen for the Air Fuel Ratio (A/F) Sensor in the DTCs MENU.
- If Still Incomplete: Check for Temporary DTCs. If no DTCs, check ECT in the DATA LIST Menu with HDS. If ECT is below 158 ºF (70 ºC), run the engine until it reaches the required temperature and repeat the procedure.
4. Air Fuel Ratio (A/F) Sensor Heater Monitor Readiness Code
Procedure:
- Start the engine.
- Idle: Let the engine idle for 1 minute.
- Check Readiness: Check the readiness code status. It should switch to “complete”.
- If Still Incomplete: Check for temporary DTCs. If no DTCs, repeat the procedure.
5. Misfire Monitor and Readiness Code, 6. Fuel System Monitor and Readiness Code, 7. Comprehensive Component Monitor and Readiness Code
These readiness codes are typically always set to “available” or “complete” because these systems are continuously monitored while the engine is running or cranking. No specific procedures are usually needed for these monitors.
8. EGR Monitor and Readiness Code
Enable Criteria:
- ECT at 176 ºF (80 ºC) or more.
Procedure:
- Connect HDS to the DLC.
- Start the engine.
- Steady Speed Drive: Drive at a steady speed of 50-62 mph (80-100 km/h) or above for more than 10 seconds in D (Automatic Transmission) or 4th gear (Manual Transmission).
- Deceleration: Decelerate from 62 mph (100 km/h) or above by fully releasing the throttle for at least 5 seconds in D or 4th gear. If the engine stops, repeat from step 2.
- Check Readiness: Check the OBD status screen for DTC P0401 in the DTC’s MENU with HDS. If it’s “passed”, readiness is complete.
- If Not Passed: Repeat from step 3 and retest.
Alt text: Close-up view of an Exhaust Gas Recirculation (EGR) valve installed on an engine.
Conclusion: Ensuring Your 8th Gen Civic is DEQ Ready
Understanding and correctly setting OBD2 readiness codes is vital for ensuring your 8th generation Honda Civic passes emissions testing. By following these procedures and using the checking methods outlined, you can proactively manage your vehicle’s readiness status. If you encounter persistent issues in setting readiness codes, or if the MIL remains illuminated, it is recommended to consult a qualified automotive technician. They can diagnose and repair any underlying problems that might be preventing your Civic from completing its emissions system self-tests and achieving a “ready” status for DEQ testing.
