Catalytic converter deactivation — clean dashboard after a cat delete.
The CAT OFF disables downstream lambda monitoring so removing the catalytic converter no longer triggers catalyst-efficiency fault codes. A common companion to exhaust upgrades.
The ECU checks catalyst efficiency through the downstream lambda sensor: on a healthy cat the rear signal stays almost flat, while a removed or dead cat lets it switch like the front one. That is what raises the classic P0420/P0430 "catalyst efficiency below threshold" codes after a decat or a collapsed substrate.
The CAT OFF patch disables the post-catalyst efficiency monitoring — rear lambda plausibility, catalyst temperature model checks and the related fault codes — while leaving the front lambda closed-loop fueling completely intact. Mixture control, fuel trims and cold-start enrichment all keep working exactly as stock.
Upload your file
Drop the original ECU read (.bin, .ori, .mod, .hex). The ECU family is identified automatically.
Pick the solution
Select the service you need — AutoMod applies it in minutes on supported ECUs, or a calibrator handles it manually.
Download the patched file
Pay with credits or directly by card — your modified file is delivered within minutes and stays downloadable for 24 hours.
Commonly ordered with: O2 OFF, SAP OFF, readiness and Stage 1/2.
On turbo petrols the decat is usually part of a bigger build — downpipe, intercooler, remap — so mention the rest of the setup when ordering: the same file can carry CAT OFF plus a Stage 1/2 calibrated for the actual hardware, which is cleaner than flashing twice.
This is the required companion to a decat pipe and also fixes marginal-efficiency warnings on some 200-cell sports cats. Pair it with the readiness service when you want the OBD monitor flags consistent for inspection.
Because the downstream lambda also feeds long-term diagnostics on some families, the patch handles the channel by function rather than by a fixed offset — rear-sensor efficiency evaluation is disabled while heater monitoring can be kept or removed depending on whether the sensor stays fitted. That is the difference between a clean delete and a file that logs heater faults a week later.
The patch targets the diagnostic only — never the sensor hardware the engine still needs. Upstream lambda regulation, fuel trims and cold-start enrichment all keep their OEM behavior; what disappears is strictly the post-cat efficiency monitor.
On V engines and twin-cat systems the efficiency monitor runs per bank — the patch handles both channels, which is why a V6/V8 does not come back a week later with a P0430 after only the P0420 side was treated.
Bosch ME7/ME9/MED9/MED17/MEV17/MEVD17 petrol families, Siemens SIM32/EMS31xx, Marelli IAW4MV/MM8/MM9 and Sagem S3000 — VAG, BMW, PSA, Fiat, Renault and Mini applications.
Typical jobs: VAG 1.8/2.0 TSI-TFSI (EA113/EA888), BMW N54/N55/B58, Mini R56 Cooper S, Ford EcoBoost/ST, Renault Sport and Fiat/Abarth 1.4 T-Jet — anywhere a decat or high-flow cat is fitted.
Most petrol ECUs of these generations read fine over OBD with KESS3 or Autotuner; locked MED17/MD1 variants go through bench mode on FLEX. Upload, patch, write back — the whole job takes minutes.
CAT OFF vs O2 OFF: the cat monitor judges catalyst efficiency through the rear sensor; O2 OFF removes the sensor channel itself. A decat with the sensor unplugged takes both — sensor staying in the pipe takes CAT OFF alone.
The front (upstream) sensor stays — it drives fueling. The rear sensor becomes optional once monitoring is off.
No. Only the diagnostic chain is removed; fueling stays on the front lambda exactly as stock.
Often yes — high-flow cats can sit just under the efficiency threshold and throw intermittent P0420 codes.
Deleted systems can be marked consistent with the separate readiness service.
Yes — each bank has its own monitor; the patch covers both banks where the engine is a V configuration.
EGR OFF
EGR valve deactivation — no more clogging faults, no limp mode.
DPF OFF
DPF deactivation — remove the filter without warnings or regeneration faults.
ADBLUE OFF
AdBlue/SCR deactivation — no more warnings, countdowns or no-start conditions.
OPF OFF
OPF/GPF deactivation for petrol engines after filter removal.