Citroen C3 Aircross Catalytic Converter

R8,500 to R25,000, and where you land depends mostly on petrol versus diesel. Petrol converters for the PureTech and THP engines are R8,500-R14,700. Diesel units are considerably more at R17,100-R24,750, because on the HDi and BlueHDi cars the converter and the particulate filter are frequently one integrated assembly. Fitting adds R1,450-R2,950, more if seized oxygen sensors have to be replaced rather than reused. Get the upstream fault diagnosed before ordering — a new converter fitted behind an unresolved cause will fail again.

Short term and short distance, if it is simply inefficient rather than physically broken up. Two things make it a bad idea beyond that. A collapsing substrate restricts the exhaust, which chokes the engine and can push debris back toward the turbo on a diesel. And a converter that is failing because of a rich mixture or an oil leak means the actual fault is still doing damage upstream. Emissions testing in some metros will also catch it at licence renewal, so it is not a problem that stays quiet indefinitely.

Left alone by everything else, 120,000-160,000 km or roughly ten years, and often longer. What shortens it here is short-trip driving that never gets the converter to its working temperature, and fuel quality that varies more than the engineers assumed. On the HDi and BlueHDi diesels the particulate filter alongside it is the more common casualty of the same driving pattern — a car that only ever does ten-minute city trips never completes a regeneration cycle, and the filter clogs long before the catalyst is worn out.

Almost always something upstream. Oil getting past valve stem seals or piston rings coats the honeycomb and kills it. A misfire dumps raw fuel into a red-hot converter and melts the substrate, which is why a running misfire should never be driven on. A lazy oxygen sensor holds the mixture rich for months and poisons it slowly. Physical damage from a speed bump or a rock cracks the shell. On the THP engines, oil consumption is worth watching precisely because of what it does downstream.

The practical measures, in order of value: park inside or somewhere overlooked and lit, fit a shield or cage over the converter at R2,450-R4,700 installed, and have the unit etched with your VIN so it is traceable and less attractive to a buyer. An alarm with a tilt sensor at R2,850-R5,650 covers the jacking that most thefts require. Higher-riding cars like the C3 Aircross and C5 Aircross are targeted more often simply because a thief can get underneath without lifting them.