Readiness Calibration is the TuningBot service that focuses on correct handling and completion of OBD-II readiness monitors, also known as Inspection/Maintenance (I/M) flags. In an OBD-II compliant vehicle, readiness codes are represented by a group of bits, each corresponding to an emission-related subsystem. When all required bits show “Passed” and no active DTCs are present, the ECU considers the onboard diagnostic tests complete.

Readiness Calibration — OBD-II Monitors & IM Flags

Readiness bits summarise whether ECU self-tests have run and completed correctly. Our Readiness Calibration aligns enabling conditions, thresholds and dependencies so that legitimate vehicles with correct hardware can complete monitors reliably after tuning or repair — without disabling or falsifying emissions-related diagnostics.

For general background on OBD-II you can refer to the On-board diagnostics article.

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What are readiness monitors

Readiness monitors are automated self-tests that the ECU runs under specific conditions of speed, load, coolant temperature and fuel level. Each monitor tracks a subsystem such as catalyst efficiency, oxygen sensor behaviour, EVAP leak detection, EGR flow or secondary air injection. Once a monitor completes its test without setting DTCs, its bit changes from Not Ready to Ready.

Some monitors are continuous (for example misfire and fuel system) and run whenever the engine is operating; others are non-continuous and require defined drive cycles, temperatures or soak times before they can execute.

When Readiness Calibration is useful

• After ECU tuning or hardware modifications that may alter monitor logic (downpipe, decat, EGR changes, sensor upgrades).
• When readiness bits remain Not Ready even though there are no DTCs and correct drive cycles have been completed.
• To restore or align enabling conditions after partial monitor deactivation or software mismatch.
• To reduce the time and number of drive cycles required for monitors to complete legitimately.

What the service includes

• Review and correction of enabling conditions for non-continuous monitors (EVAP, oxygen sensors, catalyst, EGR, secondary air, etc.).
• Adjustment of thresholds and dependencies so that each monitor can complete correctly under standard OEM conditions.
• Verification of cross-links between related tests (for example O₂ vs catalyst, EVAP vs fuel level and temperature).
• Bench and dyno validation with reference drive cycles to confirm readiness completion on real vehicles.

Recommended procedure

1. Start from a stable or stock ECU file and clear all fault codes and adaptations.
2. Verify correct operation of sensors and actuators relevant to emissions and OBD-II monitors.
3. Flash the Readiness Calibration file and perform a full monitor reset with your diagnostic tool.
4. Execute the OEM-recommended drive cycle (temperature, speeds, stops and deceleration phases).
5. Check readiness bits with your scan tool and confirm completion before inspection or emissions testing.

Legal & technical notice

This calibration is designed to assist with correct monitor alignment and validation. It must not be used to disable, mask or falsify emission-related functions where prohibited. Mechanical faults or inactive systems (for example removed catalysts or EGR hardware) must be repaired or restored to achieve legitimate readiness completion.

Local regulations and test procedures determine which monitors are mandatory for inspection; ensuring compliance and lawful use remains the responsibility of the user. For an overview of all available ECU services you can consult the ECU Services coverage page before requesting a file.

If your original file is ready and the emissions hardware is intact, you can upload it via Tune Your File and request the Readiness Calibration service from the TuningBot team.