Failed Repair: P0420 Returned After Converter Replacement
The replacement converter did not solve an upstream mixture and oil-consumption condition that continued to damage catalyst performance.
Category Failed Repairs
Cases that examine why an earlier repair did not solve the original symptom.
Failed Repair: New Battery, Same Overnight Discharge
Battery replacement restored short-term capacity but did not address a module that kept waking after shutdown.
Failed Repair: Coils Replaced but the Misfire Stayed
All coils were replaced even though the misfire remained on one cylinder and a mechanical sealing test had not been performed.
Failed Repair: A/C Recharged Without Finding the Leak
Cooling returned briefly after adding refrigerant, then faded because charge mass was never measured and the leak was not repaired.
Failed Repair: ABS Sensor Replaced, Tone Ring Still Damaged
The code location led to sensor replacement, but a cracked or contaminated encoder continued to distort the signal once per wheel revolution.