Understanding your car’s diagnostic trouble codes (DTCs) is crucial for maintaining its health and performance. The 420 Obd2 scanner is a valuable tool for any car owner or DIY mechanic looking to quickly identify and address potential issues. This guide provides a comprehensive, step-by-step walkthrough on how to use the 420 OBD2 diagnostic tool to retrieve these important trouble codes, empowering you to understand your vehicle’s condition and take informed action.
Utilizing Your 420 OBD2 Diagnostic Tool Effectively
It’s vital to remember that a DTC is just the starting point in diagnosing a car problem. Never replace parts solely based on the code definition provided by your 420 OBD2 scanner. Each code has specific diagnostic procedures outlined in your vehicle’s service manual. These procedures include detailed testing guidelines and flowcharts designed to pinpoint the exact location of the fault. Always refer to your vehicle’s service manual for complete and accurate testing procedures before undertaking any repairs.
Step 1 – Ensuring the Ignition is OFF
| | Turn the car ignition to the OFF position before starting the diagnostic process. |
Step 2 – Locating the Data Link Connector (DLC)
| | Find your vehicle’s 16-pin Data Link Connector (DLC), usually located under the dashboard on the driver’s side. |
Step 3 – Connecting the 420 OBD2 Scanner to the DLC
Carefully connect the cable connector from your 420 OBD2 scanner to your vehicle’s DLC. The connector is designed to fit only one way, ensuring correct orientation.
Note: If you encounter resistance when connecting the cable, try rotating the connector 180 degrees. If you still face difficulties, inspect both the scanner’s connector and the vehicle’s DLC for any signs of damage or debris that might be obstructing the connection. Once properly connected, the car symbol should appear on your 420 OBD2 scanner, indicating a successful power connection established through the vehicle’s DLC.
Step 4 – Turning the Ignition ON (Engine OFF)
| | Turn the ignition key to the ON position, powering up the vehicle’s electrical systems, but DO NOT start the engine. |
Step 5 – Automatic Link to the Vehicle’s Computer
Your 420 OBD2 diagnostic tool is designed to automatically establish a link with your vehicle’s onboard computer system.
If the scanner does not power on at this stage, it typically indicates a lack of power at the vehicle’s DLC connector. In such cases, check your vehicle’s fuse panel and replace any blown fuses. If replacing the fuse doesn’t resolve the issue, consult your car’s repair manual to identify the correct fuse or circuit related to the Powertrain Control Module (PCM) and perform any necessary repairs before proceeding with the diagnostic process using your 420 OBD2 scanner.
Step 6 – Protocol Check and Communication Establishment
| | The 420 OBD2 scanner will automatically begin checking your vehicle’s computer to identify the communication protocol it uses. |
The tool will display “AUTO-LINK” as it attempts to identify the computer’s communication protocol. A progress bar will be shown while a communication link is being established.
If the 420 OBD2 scanner fails to connect to the vehicle’s computer, a “Communication Error” message will appear. If you encounter this error, take the following steps:
- First, ensure that your vehicle is OBD2 compliant. Most vehicles manufactured after 1996 in the US are OBD2 compliant, but it’s always best to verify.
- Double-check the connection at the DLC to ensure it is secure.
- Confirm that the ignition is turned ON (but engine not started).
- Turn the ignition OFF, wait for about 5 seconds, and then turn it back ON to reset the computer system.
- Press and hold the DTC/FF/ DOWN ▼ button on your 420 OBD2 scanner to retry the connection.
If the “Communication Error” persists on the scanner’s LCD display, it indicates a persistent communication problem, meaning the 420 OBD2 tool is still unable to communicate with the vehicle’s computer. In this situation, repeat the reset procedure: turn the ignition key OFF, wait 5 seconds, and then turn it back on. If the problem continues, there might be an issue with your vehicle’s computer system or wiring that requires professional diagnosis.
Step 7 – VIN Decoding (Automatic)
If your 420 OBD2 scanner successfully decodes the Vehicle Identification Number (VIN) of your vehicle, the OBD2 results screen will be displayed automatically. In this case, proceed directly to step 9.
Step 8 – Manual Vehicle Selection (If VIN Decoding Fails)
If the 420 OBD2 scanner is unable to automatically decode the VIN, one of two scenarios will occur:
If your vehicle has stored OEM Diagnostic Trouble Codes (DTCs), the “Select Make” screen will appear on your 420 OBD2 scanner.
- Use the DOWN ▼ button to navigate through the list and select the make of your vehicle. Once you have selected the correct make, press the MENU/ENTER↵ button to confirm your selection. After this, proceed to step 9 to retrieve the DTCs.
If your vehicle does not have any OEM Diagnostic Trouble Codes stored, the screen will display the result as “Global OBD2“.
In this case, proceed directly to step 9.
Step 9 – Retrieving Diagnostic Trouble Codes (DTCs) and Data
| | After a short period (approximately 2-3 seconds), the 420 OBD2 diagnostic tool will retrieve and display any Diagnostic Trouble Codes (DTCs), Monitor Status information, and Freeze Frame Data that are stored in your vehicle’s computer memory. |
The 420 OBD2 scanner will only display a code if any trouble codes are present in the vehicle’s computer.
If no codes are found, the message “No Powertrain DTCs or Freeze Frame Data presently stored in the vehicle’s computer” will be displayed on the screen.
Refer to the “DISPLAY FUNCTIONS” section of your 420 OBD2 scanner manual for a detailed description of all display elements and their meanings.
Note: For codes with lengthy definitions, a small arrow indicator will appear in the upper or lower right-hand corner of the display area. This arrow signifies that additional information is available beyond what is currently displayed. If a definition is not available for the currently displayed code, an advisory message will be shown on the 420 OBD2 scanner screen.
Step 10 – Interpreting DTCs Using the Display and LEDs
| | Use the LCD display on your 420 OBD2 scanner in conjunction with the green, yellow, and red LEDs to read and interpret the Diagnostic Trouble Codes. These LEDs provide quick visual cues about the engine system’s condition. |
A. Green LED: A solid green LED indicates that all engine systems are functioning correctly and are in an “OK” state, running under normal conditions. All vehicle monitors are active and performing their diagnostic tests, and importantly, no trouble codes are present. The 420 OBD2 scanner’s LCD display will also show the message “No DTC” to further confirm this healthy system status.
B. Yellow LED: A yellow LED indicates one of two possible conditions:
- PENDING CODE PRESENT: If the yellow LED is illuminated, it may signal the presence of a Pending code. Check the LCD display of your 420 OBD2 scanner for confirmation. A Pending code is confirmed by the display of a numeric code along with the word “Pending”. Pending codes indicate intermittent issues or problems that have not yet occurred enough times to trigger a permanent DTC and the check engine light.
- MONITOR NOT RUN STATUS: If the yellow LED is lit, but the display shows a zero (indicating no DTCs currently stored in the vehicle’s computer memory), it means that some of the vehicle’s supported monitors have not yet run and completed their diagnostic testing cycles. In this case, any Monitor icons on the display that are blinking are those that have not yet completed their tests, while solid Monitor icons represent monitors that have successfully run and completed their diagnostic testing.
C. Red LED: A red LED signals that there is a problem with one or more of the vehicle’s systems. The red LED also serves as an indicator that Diagnostic Trouble Code(s) are present. When the red LED is illuminated, the Malfunction Indicator Lamp (MIL), commonly known as the “Check Engine” light, on the vehicle’s instrument panel will also typically be illuminated. This is a clear warning that your vehicle has detected a problem that requires attention.
Note: Diagnostic Trouble Codes (DTCs) that begin with “P0” are classified as generic codes. These generic codes are standardized across all OBD2-equipped vehicles, regardless of manufacturer. Conversely, DTCs that start with “P1”, “P2”, and “P3” are manufacturer-specific codes. These codes are defined by the vehicle manufacturer and are specific to their makes and models. When diagnosing issues, understanding whether a code is generic or manufacturer-specific can provide valuable context.
Step 11 – Navigating Multiple DTCs
| | If your 420 OBD2 scanner retrieves more than one Diagnostic Trouble Code (DTC), you will need to navigate through them to view each code and its associated data. |
Press the M/ENTER↵ button, as needed, to view Freeze Frame data that is associated with the first DTC (DTC #1). Freeze Frame data provides a snapshot of the vehicle’s operating conditions at the moment the DTC was recorded.
To scroll through and view additional stored codes, press and release the DTC/FF/DOWN ▼ button. Each press of the DTC/FF/DOWN ▼ button will advance the 420 OBD2 scanner to the next DTC in the sequence, displaying each one until all stored DTCs in the memory have been shown.
| | Alternatively, some 420 OBD2 scanner models may use different button configurations for navigation. Press the ENTER ↵ button, as necessary, to view Freeze Frame data for DTC #1. |
Press and release the DOWN ▼/UP ▲ buttons to navigate through additional stored codes. Each press of the DOWN ▼/UP ▲ buttons will cause the 420 OBD2 tool to scroll and display the next DTC in sequence until all DTCs have been displayed.
Depending on your 420 OBD2 model, you may need to press the FF/DTC buttons to toggle between viewing DTCs and their associated Freeze Frame data. Consult your scanner’s user manual for specific button functions and navigation instructions.
Step 12 – Returning to the Priority Code
When you have viewed the last retrieved DTC and then press the DTC/FF/DOWN ▼ button (or the down navigation button on your specific 420 OBD2 model) again, the diagnostic tool will typically loop back and return to displaying the ‘Priority’ code, usually the first code retrieved or the most critical one. This allows for easy review of all codes in a cycle.
Step 13 – Determining Engine System Condition
To determine the overall condition of your vehicle’s engine system(s), carefully review the display on your 420 OBD2 scanner for any retrieved Diagnostic Trouble Codes, their corresponding code definitions, and any available Freeze Frame data. Pay close attention to the green, yellow, and red LEDs, as they provide immediate visual cues about the severity and nature of any detected issues.
If DTCs were found and you decide to undertake the repairs yourself, it is essential to begin by consulting your vehicle’s service manual. This manual contains detailed flowcharts, step-by-step testing instructions, and specific testing methods that are directly related to each retrieved code. Following these manufacturer-recommended procedures is crucial for accurate diagnosis and effective repair.
