✅ Fixed
Downstream O2 sensor replaced first $85. Code returned 1000 miles later. Catalytic converter genuinely worn — replaced with quality aftermarket $320. Passed emissions test.
Toyota Prius 2012 Catalytic converter P0420 code
Safe to Drive?
⚠️ Drive with Caution
Urgency Level
🟡 Monitor Closely
Toyota Prius 2012 P0420 catalytic converter efficiency below threshold. Car runs fine. Failed emissions test. 175410 km. This fault code is stored when the engine control unit detects a specific fault condition. Common causes include sensor failures, wiring faults, and component wear. Always read additional fault codes before replacing parts — multiple codes together provide a clearer diagnosis. Clear the code after repair and test drive to confirm the fault does not return.
🔍 Symptoms
📍 Toyota Prius
⚠️ P0420 fault code
⚙️ Possible Causes
Fault code P0420 detected
Toyota Prius
Possible: Downstream O2 sensor replaced first $85. Code returned 1000 miles later. Catalytic converter genuinely worn — replaced with quality aftermarket $320. Passed emissions test.
Repair / Solution
Based on 97 driver confirmations
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