Diagnostic Scan

Perform a diagnostic scan using an OBD-II scanner to retrieve fault codes and system data from the vehicle's powertrain control module and other onboard systems.

Warnings

Tools required

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure ignition is in OFF position
3. Locate OBD-II diagnostic port under driver side dashboard, left of steering column near the hood release
4. Ensure no aftermarket devices are plugged into the OBG-II port; remove if present

Procedure

1. 1

   Connect Diagnostic Scanner
   Plug the OBD-II scanner connector into the 16-pin diagnostic port located under the driver side dashboard. Ensure the connection is fully seated and secure. The port is a trapezoid shape and the connector will only fit one way.
2. 2

   Turn Ignition to ON Position
   Turn the ignition key to the ON position (or press the start button twice without pressing the brake pedal). Do not start the engine. All dashboard lights should illuminate. Wait for the scanner to power on and establish communication with the vehicle's modules.
3. 3

   Initialize Scanner Communication
   Follow your scanner's prompts to establish communication. Most scanners will auto-detect the vehicle as a 2018-2024 Honda Accord. If manual entry is required, select Honda, Accord, the correct model year, and 1.5L Turbo engine. Wait for the scanner to complete the initial handshake with all available control modules.
4. 4

   Read Diagnostic Trouble Codes (DTCs)
   Navigate to the 'Read Codes' or 'Scan for Codes' function on your scanner. Allow the scanner to query all vehicle control modules including Engine/Powertrain (PCM), Transmission (TCM), ABS, SRS Airbag, and Body Control systems. Record all DTCs displayed, including the code number (e.g., P0300), system location, and code description.
5. 5

   Review Freeze Frame Data
   For each DTC found, access the freeze frame data which captures operating conditions at the moment the code was set. Record key parameters such as engine RPM, vehicle speed, coolant temperature, throttle position, fuel trim values, and any other relevant sensor readings. This data is critical for accurate diagnosis.
6. 6

   Check Live Data Stream
   Navigate to the live data or PID (Parameter Identification) display. Monitor real-time sensor values including oxygen sensors, mass airflow sensor, intake air temperature, coolant temperature, fuel trims, ignition timing, and boost pressure (critical for turbo operation). Compare values against normal operating ranges for the 1.5L turbo engine. Note any values that appear out of specification.
7. 7

   Check Readiness Monitors
   Access the I/M Readiness or Monitor Status screen. Verify the status of all emission system monitors including Catalyst, EVAP, O2 Sensor, O2 Heater, EGR (if equipped), and Misfire monitors. Record which monitors show 'Ready' or 'Complete' versus 'Not Ready' or 'Incomplete'. Incomplete monitors may indicate recent code clearing or an incomplete drive cycle.
8. 8

   Document Vehicle Information
   Record the Vehicle Identification Number (VIN), current odometer reading, and any other vehicle-specific information displayed by the scanner. Note the calibration ID and software version of the PCM if available, as this may be relevant for technical service bulletins or reflashing procedures.
9. 9

   Save or Print Diagnostic Report
   If your scanner has save or print functionality, create a complete diagnostic report with all codes, freeze frame data, and monitor status. If not available, ensure all information has been accurately recorded manually. Take photos of scanner screens if needed for documentation.
10. 10

    Disconnect Scanner and Return to Normal
    Turn the ignition to OFF position. Disconnect the OBD-II scanner from the diagnostic port. Reinstall any port covers or trim if removed. If codes were only read and not cleared, they will remain stored in the vehicle's memory for further diagnosis and repair.

Reassembly

1. No reassembly required for diagnostic scan procedure
2. If codes were cleared during scan, vehicle will need to complete a full drive cycle to reset readiness monitors

Verification

• Confirm all diagnostic trouble codes and descriptions were accurately recorded
• Verify scanner disconnected and diagnostic port is accessible for future use
• Review recorded data to determine next diagnostic or repair steps based on fault codes found
• If no codes are present but concerns exist, verify concern occurs during test drive and monitor live data during symptom occurrence

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