EGR Valve and Cooler Clogging & Head Gasket Failure
SeriousEngineAt high mileages, carbon buildup in the Exhaust Gas Recirculation (EGR) system restricts flow, increasing cylinder temperatures and eventually blowing the head gasket. This is the most common major engine failure on high-mileage CT 200h cars, particularly those used for frequent short journeys that prevent the EGR system from reaching self-cleaning temperatures.
Loud knocking sound on cold start, Rough idle and coolant consumption, Check engine light with P0401 code, White smoke from exhaust on startup
- Listen for unusual rattling when petrol engine engages
- Inspect under oil cap for mayonnaise-like emulsion
- Confirm no white smoke from exhaust after cold start