Posts Tagged: exhaust leak diagnosis
P0420 After Replacing Catalytic Converter? What to Check
Why Your P0420 Code Came Back After Installing a New Catalytic Converter Quick Summary Getting a P0420 after replacing the catalytic converter can be frustrating, especially after spending hundreds or even thousands of dollars on a new converter. In many cases, the new converter isn’t actually the problem. A P0420 code that returns after converter replacement because you didn’t fix the underlying cause that killed the previous converter. The most common causes of catalytic converter failure are: 1) Misfires due to an ignition problem (worn spark plugs or faulty ignition … Read More
How to Diagnose a P0420 catalytic converter code
How I Diagnose P0420 Catalytic Converter code the Right Way (Without Guessing or Throwing Parts) Quick Takeaway Diagnose a catalytic converter P0420 or P0430 code by verifying fuel control, misfire data, exhaust integrity, oxygen sensor behavior, and contamination risks. Most converters fail because something else killed them first—and if you don’t find that root cause, the replacement will fail too. Article Why P0420 and P0430 Are So Often Misdiagnosed I see P0420 and P0430 misdiagnosed more than almost any other emissions code. Shops replace oxygen sensors, then catalytic converters, and … Read More
P0420 or P0430 No Other Codes? Here’s What I Check First
P0420 or P0430 With No Other Codes: How I Diagnose It Without Wasting Money Quick Summary If you have a P0420 or P0430 with no other codes, don’t automatically assume the catalytic converter is bad without additional testing. In my experience, the converter is often the culprit, but it’s not the only possibility. I always begin by confirming there are truly no additional engine, fuel trim, misfire, or oxygen sensor codes, then inspect for exhaust leaks and analyze live scan data before recommending an expensive converter replacement. Following a logical … Read More