OBD2 Readiness Monitors: What They Are (Inspection/MOT)
Key Takeaway
Need to pass an emissions inspection? You must understand readiness monitors first.
What Are Readiness Monitors?
Readiness monitors are self-tests the vehicle runs to verify that emissions systems are working. They must be "complete" (or "ready") to pass an emissions inspection.
The Monitors
| Monitor | What It Tests | Type |
|---|---|---|
| Catalyst | Catalytic converter efficiency | Continuous |
| Heated Catalyst | Heated cat warmup | Continuous |
| EVAP | Fuel vapor system integrity | Non-continuous |
| Secondary Air | Secondary air injection | Non-continuous |
| Oxygen Sensor | O2 sensor response | Non-continuous |
| O2 Heater | O2 sensor heater function | Non-continuous |
| EGR | Exhaust gas recirculation | Non-continuous |
| Misfire | Engine misfire detection | Continuous |
| Fuel System | Fuel delivery control | Continuous |
Why Monitors Reset
Clearing codes (Mode 04) or disconnecting the battery resets all monitors to "not ready." They need 50-100 miles of varied driving to complete again.
How to Complete Monitors
Drive a mix of city and highway for 50-100 miles. Include cold starts, steady highway cruising, and stop-and-go city driving. Most monitors complete within 2-3 drive cycles.
ProHow Steer Helps
Steer shows you the real-time status of all readiness monitors, so you know when you're ready for inspection.
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