EVAP Off Service is a professional ECU calibration that disables the Evaporative Emission Control System logic in the ECU software. The EVAP system prevents fuel vapours from escaping the tank into the atmosphere by storing them in a charcoal canister and periodically purging them into the intake. When these components fail or are removed in custom builds, the ECU logs DTCs and may keep readiness monitors incomplete.

EVAP Off Service – Evaporative Emission Control System

By deactivating EVAP logic and related diagnostic checks in the ECU, the EVAP Off Service prevents purge-flow and tank-pressure errors from triggering DTCs, MIL lights or readiness failures on vehicles where the EVAP system has been deleted or heavily modified. All non-EVAP engine protection and diagnostic functions remain active.

For a general overview of how evaporative emission systems work you can refer to the
Evaporative Emission Control System article.

When to use the EVAP Off Service

• After removing or disabling the charcoal canister or purge control valve during tuning or custom builds.
• When the EVAP system causes recurring DTCs such as P0441, P0455, P0456, P0457 or related readiness failures.
• For vehicles converted for motorsport, race or off-road applications where the EVAP system is no longer used.
• To eliminate check-engine lights caused by tank pressure monitoring or purge flow errors.

Technical overview

The EVAP subsystem interacts with multiple ECU components, including:

• Purge control valve (N80 / solenoid) – manages fuel vapour flow from the canister to the intake manifold.
• Tank pressure sensor – detects leaks and verifies system integrity during diagnostic tests.
• Vent control – allows filtered air into the system while the ECU performs purge or leak tests.

When these components fail or are deleted, the ECU detects abnormal behaviour, logs error codes and sets the EVAP readiness bit to “Not Complete”. Our calibration safely disables EVAP-specific diagnostic checks and readiness logic while keeping other emission systems (oxygen sensors, catalyst efficiency, etc.) fully functional.

How the EVAP Off Service works

1. Assessment: We review the ECU ID and DTC structure to identify EVAP-related dependencies and monitors.
2. Calibration: We adjust purge, tank pressure and EVAP monitor logic to bypass the EVAP diagnostic routines in a controlled way.
3. Verification: Once the modified file is flashed, the ECU runs normally with EVAP monitoring disabled and all other systems intact.

Compatibility

The EVAP Off Service is available for many petrol ECUs, including Bosch, Siemens/Continental, Delphi, Denso and Magneti Marelli families. You can use the module below to verify coverage for your ECU type and software version.

Because EVAP systems vary greatly between manufacturers, our approach focuses on platform-specific behaviours, including leak detection thresholds, purge command strategies, and tank pressure validation logic. This ensures that each EVAP off service file behaves consistently without unwanted side effects even on vehicles equipped with more complex OBD-II readiness structures, hybrid fuel systems or performance-oriented intake layouts.

For a wider view of all available ECU strategies you can also visit the ECU Services overview page before submitting your file.

Legal & technical notice

This service is intended exclusively for motorsport, track or off-road vehicles, or for custom fuel systems where EVAP hardware is not present and where such modifications are permitted by local law. It must not be used to falsify emission checks or bypass legal requirements for vehicles operated on public roads.

Any mechanical faults or removed emission components outside the EVAP system (such as catalysts or EGR valves) must be repaired or reinstalled to maintain safe and lawful operation. Ensuring compliance with regional regulations is the sole responsibility of the vehicle owner and operator.

If your original ECU file is ready and the vehicle is configured for motorsport or off-road use, you can upload it through Tune Your File and request the EVAP Off Service from the TuningBot team.