What Dacia codes (P0420) actually mean on Dacia engines — the real cause, the common misdiagnosis, and the honest UK repair cost.
These are the OBD fault codes we see most often on Dacia vehicles in the workshop, with the real cause on Dacia engines rather than the generic textbook definition, plus the honest independent-garage cost.
Dacia fault codes explained
- P0420 — Catalyst efficiency below threshold on Dacia — Renault-shared 1.5 dCi K9K and 0.9 TCe cat aging. Typical UK cost £150–£550.
Codes are generic across manufacturers, but the fix is not. The same code on a Dacia usually points at a different component than it would on another make, which is why a make-specific diagnosis saves money before any parts are bought.