Citroen Diagnostic Trouble Codes

OBD2 fault codes seen on Citroen vehicles, with what each code means and the Citroen models it shows up on. Each code's page has its typical repair cost range.

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Fuel System

P0171Moderate

System Too Lean (Bank 1)

Citroen C3 • 2009-2024

On Citroen petrol engines, P0171 usually comes from air entering after the MAF sensor: a split or perished…

Emissions

P0420Moderate

Catalyst System Efficiency Below Threshold (Bank 1)

Citroen C4 • 2008-2024

On Citroen petrol engines (C3, C4, C5 with the 1.2 PureTech and 1.6 VTi/THP, shared with Peugeot), P0420 is…

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