故障コード索引 · medium
P0421
Warm-up catalyst efficiency below threshold (bank 1)
Warm-up catalyst efficiency below threshold (bank 1)
Applies to: Generic SAE definition - verify applicability to the specific X-TYPE variant · Confidence: Generic SAE definition (not Jaguar-specific)
Common causes
- Pre-catalyst degraded
- Sensor fault
- Exhaust leak
Quick checks
- Scan access: Generic OBD-II scan tool
Typical fixes
- Rule out sensors and exhaust leaks first
- Replace the manifold/pre-cat assembly