P0421 Diagnostic Trouble Code Discussion for March 2004
Warmup Catalyst Efficiency Low (Bank 1)
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| Help Request | Posted | |
| 2000 Volkswagen Passat GLS 2.8L MIL Lamp on VIN: B8YE230886 P0421: Warm Up Catalyst Efficiency Below Threshold Bank 1. ... Up Catalyst Efficiency Below Threshold (Bank 2) ,P0421 Warm Up Catalyst Efficiency Below Threshold (Bank 1) Customer had car at dealer first with code P0300, P0431,P0421 had plugs replaced and codes cleared . Mil light c... |
March 24, 2004 | |
| 1997 Mazda Protege DX 1.5L Poor Idle Quality, MIL Lamp on VIN: JM1BC141XV P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). ... check engine lite on.It had code P0421 cat converter warm up bank 1 S1.The lower cat and both O2 sensors were replaced.After driving about 15 miles the engine runs rough for a split second and the check engine light comes on.The engine straitened out and r... |
March 31, 2004 |
