[Solved] Citroen C4 GP 1.6 HDI 109KM - Errors: P0401, P0490 and P1459

The discussion revolves around the Citroen C4 GP 1.6 HDI experiencing EGR-related errors: P0401, P0490, and P1459, leading to symptoms such as choking and jerking during acceleration. Users suggest checking various parameters like vacuum, turbo boost, throttle position, and EGR valve operation. The EGR valve is confirmed to be electric, and issues with air flow measurements are noted, particularly spikes in measured air flow under load. Several users recommend performing logs while driving, checking connections, and considering the replacement of the MAF sensor, which ultimately resolved the jerking issue for the original poster. The importance of EGR adaptation and monitoring turbo pressure is also emphasized.
Summary generated by the language model.