Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
To Decide Diagnostic Trouble Code Test's Status
By reading out the diagnostic trouble code with associated status identifier, then status for the diagnostic trouble code test that detects the malfunction and generates the diagnostic trouble code, is obtained.
Example 1, Permanent malfunction
Status identifier:
| Malfunction found the last time that the diagnostic trouble code test was run during current driving cycle | = | Yes | |
| Malfunction found at least once during the current driving cycle | = | Yes | |
| Malfunction found at least once during the current and previous driving cycles | = | Yes | |
| Malfunction found recently since erasing of diagnostic trouble codes | = | Yes | |
| Diagnostic trouble code test run at least once since erasing of diagnostic trouble codes | = | Test run | |
| Malfunction found at least once since erasing of diagnostic trouble codes | = | Yes | |
| Diagnostic trouble code test run at least once during the current driving cycle | = | Test run | |
| Request for lit warning light/text message | = | Yes |
The diagnostic trouble code test has been run in both current driving cycle and in earlier driving cycles. Malfunction has been detected both in current driving cycle and in previous driving cycle, which indicates that the malfunction is active right now. The control module has requested lighting of the warning light.
Conclusion: Permanent malfunction.
Assessment: Very good chance to repeat the customer symptom and thus succeed with troubleshooting, as the malfunction has been found in current and in previous driving cycle. Since the malfunction has been detected during the present run cycle, it does not really matter for troubleshooting if the malfunction has been detected in all previous driving cycles or not. If this information is supplemented with the counters' values you can decide how "permanent" the malfunction is.
If the vehicle is stationary, e. g., with the ignition on, this means that the test runs directly when the ignition is turned on. This makes it easier to both fins the malfunction and to verify that the malfunction cause has been take care of.
Example 2, Unknown status
Status identifier:
| Malfunction found the last time that the diagnostic trouble code test was run during current driving cycle | = | No | |
| Malfunction found at least once during the current driving cycle | = | No | |
| Malfunction found at least once during the current and previous driving cycles | = | Yes | |
| Malfunction found recently since erasing of diagnostic trouble codes | = | Yes | |
| Diagnostic trouble code test run at least once since erasing of diagnostic trouble codes | = | Test run | |
| Malfunction found at least once since erasing of diagnostic trouble codes | = | Yes | |
| Diagnostic trouble code test run at least once during the current driving cycle | = | Test not run | |
| Request for lit warning light/text message | = | No |
The diagnostic trouble code test has been run in previous run cycles but not in current driving cycle. Malfunction has been detected in previous run cycle, but not in current driving cycle since the test has not started. Warning light is on.
Conclusion: Unknown status
Assessment: Since the test has not started in the current driving cycle it is not possible to decide if the malfunction is "active" right now. First read the diagnostic trouble code information and try to obtain conditions so that the test is started and run, which enables detection of the malfunction. If the malfunction is detected, chances are very good to repeat the customer symptom, and thus succeed with troubleshooting as the malfunction has been found in the current driving cycle.
If the malfunction was not detected even though conditions are fulfilled, then chances are less good to repeat the customer symptom, and thus succeed with troubleshooting as the malfunction has not been found in the current driving cycle.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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