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.
Monitored Emission Control Systems
The OBD II System monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following:
- Comprehensive component monitoring - Emission related inputs and outputs
- EGR system
- Misfire monitoring
For the specific DTCs required for each system, refer toInspection/Maintenance (I/M) System DTC Table .
| Step | Action | Yes | No |
|---|---|---|---|
| 1 |
IMPORTANT:
Any DTCs set, even those not listed in the Inspection/Maintenance system DTC table, may prevent the required DTCs from running.
|
Go to Step 3 | Go toStep 2 |
| 2 |
|
Go to Inspection/Maintenance (I/M) Complete System Set Procedure | Go to Step 3 |
| 3 | Observe the I/M System Status display, with a scan tool. Is more than one system indicating a NO status? |
Go to Inspection/Maintenance (I/M) Complete System Set Procedure | Go to the I/M System Set Procedure for the indicated system that did not update to YES |
NO RELATED
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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.