1996 Chevrolet K1500 5.7L Vortec P0430 Code After Exhaust Upgrade to 2 into 2 Dual Flowmaster
My 1996 Chevrolet K1500 with a 5.7L Vortec engine started throwing the P0430 diagnostic trouble code shortly after upgrading the exhaust from stock 2 into 1 to a 2 into 2 Dual Flowmaster system. I replaced the oxygen sensor, but the issue persists. The new exhaust is in excellent condition with no visible leaks and the truck runs smoothly otherwise. Could this be related to the exhaust upgrade? If so, this scenario has likely been encountered many times before—there may be a well-known solution. Any insights or fixes from owners who have gone through a similar setup? Thanks in advance for your help.
Exhaust leaks near the catalytic converter, or using aftermarket converters, can trigger the P0430 code. Even minor leaks in this area may disrupt oxygen sensor readings and cause the engine control module to register a faulty downstream oxygen sensor.