What causes P1421 on a Ford?

Melted catalyst substrate from prolonged misfire Thermal shock from cold water on a hot converter Contamination from coolant or oil burning Impact damage to the converter shell Severe over-fueling overheating the bed

How do I fix P1421 on a Ford?

Inspect the converter for rattling substrate Fix the misfire or contamination cause first Check exhaust backpressure Verify with temperature readings across the converter Replace the damaged converter after root-cause repair

P1421 Catalyst Damage Detected

Q: What does P1421 mean on a Ford?

P1421 — Catalyst Damage Detected. Applies to Ford models with catalyst damage monitoring.

Category: Powertrain - Auxiliary Emissions Controls
Severity: Check Engine Light
Applies to: Ford models with catalyst damage monitoring

What does P1421 mean on a Ford?

P1421 — Catalyst Damage Detected. This Ford-enhanced code applies to Ford models with catalyst damage monitoring.

Common causes of P1421

Melted catalyst substrate from prolonged misfire
Thermal shock from cold water on a hot converter
Contamination from coolant or oil burning
Impact damage to the converter shell
Severe over-fueling overheating the bed

How to fix P1421

Inspect the converter for rattling substrate
Fix the misfire or contamination cause first
Check exhaust backpressure
Verify with temperature readings across the converter
Replace the damaged converter after root-cause repair