P0420 Diagnostic Trouble Code Discussion for September 2025
Catalyst Efficiency Below Normal (Bank 1)
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| Help Request | Posted | |
| 2005 GMC Savana 2500 4.8L Hesitation, Cuts out, Misfire VIN: 1GTGG25V95 P0420: Catalyst System Low Efficiency (Bank 1). customer complained of the vehicle running rough and occasionally stalling after talking some more found its most common after filling up with fuel. customer also stated he fills the gas all the way up a couple clicks after the pump stops i advised him to ... |
September 19, 2025 | |
| 2005 GMC Savana 2500 4.8L Hesitation, Cuts out, Misfire VIN: 1GTGG25V95 P0420: Catalyst System Low Efficiency (Bank 1). customer complained of the vehicle running rough and occasionally stalling after talking some more found its most common after filling up with fuel. customer also stated he fills the gas all the way up a couple clicks after the pump stops i advised him to ... |
September 20, 2025 |
