Cat Off - Catalytic Converter Deactivation
ECU software support for decat / catless exhaust builds, stopping the resulting fault codes.
The catalytic converter cleans the exhaust but restricts flow, so some performance builds use a decat or a catless downpipe in its place.
Once the catalyst is gone, the O2 and lambda sensors read abnormally, and the ECU logs faults, lights the check-engine lamp and can drop into limp mode. The car may run poorly even though the mechanical change itself is sound.
Cat Off disables the cat-related monitoring, the O2 and lambda handling and the emission self-checks in the ECU, then re-trims the mixture so the build runs cleanly. It is applied together with the physical decat and brings a small flow gain and a freer exhaust note.
It works alongside Lambda Off and DTC Off, which together tidy up the remaining sensor and warning-light issues. Because it removes an emission-control device, Cat Off is intended for off-road, motorsport or export use and may not be legal for road use in many countries, so the owner should check local regulations.
Advantages & Features
- Supports decat / catless downpipe builds
- Clears cat and O2 fault codes
- Turns off the related check-engine light
- Freer exhaust flow and note
- Prevents monitoring-driven limp mode
- Fully reversible to stock
Related solutions
Price
Paid with credits from your account balance. The credit amount for your ECU is shown after the file is analysed, before you confirm. See credit packages
Frequently Asked Questions
What does Cat Off do?
It adapts the ECU to a decat or catless exhaust: catalyst-efficiency monitoring and the related fault codes are disabled so the engine runs cleanly without the converter.
Who is Cat Off for?
Track and motorsport builds with a decat or sports-cat exhaust, and workshops where the catalyst has been removed or replaced.
Which file do I need to upload?
A full read of the original ECU file. Lambda Off is usually included or selected with it.
How long does Cat Off take?
Typically 10-45 minutes when a tuner prepares it.
Is Cat Off reversible?
Yes. Flash the original file back when the catalyst is refitted.
Is Cat Off legal?
Removing the catalytic converter is not permitted for road use in most countries and affects inspection and insurance. The service is for off-road and motorsport use only.