P0420 Diagnostic Trouble Code Discussion for July 2015
Catalyst Efficiency Below Normal (Bank 1)
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| Help Request | Posted | |
| 1999 Chevrolet Silverado 1500 4.3L Poor Idle Quality, Misfire VIN: 1GCEC14W0X P0420: Catalyst System Low Efficiency (Bank 1). Hi Kids This Truck Has Steady Misfire Spark is Good. Tried New Plug no Help. Hear is What I Want Help With. I Went to Check Exhaust Back Pressure. Removed EGR Valve So I Could Test Pressure at EGR Exhaust Port. Whith the Engine Running The Pressure Bounces up ... |
July 15, 2015 | |
| 2005 Cadillac STS 4.6L Poor Idle Quality, Misfire, MIL Lamp on VIN: 1G6DC67A85 P0420: Catalyst System Low Efficiency (Bank 1). Random misfires, intermittently, when is misfiring B1 avg injector pulse is 3.5ms and B2 avg injector pulse is 7.3ms. Lambda values per bank are 1.250 and 0.950 not certain which value is for which bank. When problem is gone all values are close to each other ... |
July 31, 2015 |
