What does a catalytic converter do?
A catalytic converter uses a coated ceramic or metallic substrate to convert carbon monoxide, hydrocarbons and nitrogen oxides into less harmful gases. Petrol cars rely on three-way cats; diesels use oxidation catalysts alongside DPF/SCR systems.
Common catalytic converter problems
- Efficiency codes (often P0420 / similar)
- Rattling from a broken substrate
- Restricted exhaust / loss of power when melted or clogged
- Sulphur smell or failed emissions test
- Theft of high-value cats (increasingly common)
Cats, O2 sensors and the ECU
Downstream O2 sensors monitor catalyst efficiency. If the cat is damaged or missing, the ECU logs faults and may illuminate the engine light. A remap will not “fix” a failed catalyst.
Remapping with the catalytic converter intact
Stage 1 maps from Torque Lab Ltd keep emissions hardware in place for road use. Performance gains come from calibration — not from removing the cat. See performance after a remap.
Legal path if your cat has failed
Replace with a type-approved catalytic converter, fix underlying misfires or rich running that damaged it, then consider a remap once the exhaust is healthy. Contact us for remapping advice in Greater Manchester.