P0421 CODE CITROËN C4 CACTUS
@user_1049645
09.07.2022 12:50
Member
This is for cactus c4 2018
My EML came on and it showed that the car didn’t recognise the catalytic converter, citron said as first route of fix, to complete a software update. 6 weeks later the EML came back on and citreon then said it needed a new cat. The car is only 4 years old and 27k miles…..cat is not damaged in any way soot levels and dbf all fine. Turns out this is a known fault with these cars……that a technical services bulletin was issued……so don’t get tricked into paying for a new cat without checking this out. Bit of a challenge, but end result it got covered under warranty!
09.07.22
03.06.25
@Sciewher22.07.2022 15:35MemberInteresting. Thank you for this information, this is useful information, if possible, continue to share such information!- @colin_gray3430.05.2025 09:50MemberThanks for sharing your experience with the P0421 code on your Citroën C4 Cactus. It's great that you managed to get it covered under warranty! I've heard similar stories from other Citroën owners, especially with the C4 Picasso and C3 models. It seems this catalytic converter recognition issue isn't limited to the Cactus. Has anyone else encountered this problem with other Citroën vehicles?
- @fish-chips30.05.2025 14:13MemberBlimey, talk about a right palaver with these French motors! I've got a mate who had a similar issue with his Berlingo. Kept getting that pesky P0421 code and the dealer was trying to flog him a new cat for a small fortune. Turns out it was just a software hiccup. Makes you wonder if these cars are more computer than automobile these days!
- @user_365709603.06.2025 07:30MemberKept getting that pesky P0421 code and the dealer was trying to flog him a new cat for a small fortune. Turns out it was just a software hiccup. Makes you wonder if these cars are more computer than automobile these days block blast free!
- @QUIETVOICES03.06.2025 08:10MemberI can confirm this isn't just a Cactus problem. My C3 diesel had the same P0421 code pop up. Dealer tried the software update, but it came back. Thankfully, I stumbled upon a forum post about the technical service bulletin and showed it to them. They grudgingly sorted it under warranty. It's worth noting that some Jumper vans have had similar issues too.
- @r.lewis03.06.2025 08:41MemberCrikey, it's like these Citroëns are playing a game of "Guess the Catalytic Converter"! But seriously, it's concerning that this seems to be a widespread issue across multiple models. Has anyone had any luck with independent garages diagnosing and fixing this, or is it strictly a dealer-only job due to the software side of things?
- @G. Cole03.06.2025 09:16MemberI've got a 2019 C4 Cactus and recently started getting the P0421 code. Was worried sick about having to shell out for a new cat, but after reading this thread, I'm feeling a bit more optimistic. Does anyone know if Citroën has extended the warranty for this specific issue, given that it's a known fault?
