P0420 Diagnostic Guide
P0420 usually means the ECM may be seeing low catalyst efficiency on Bank 1.
Article vehicle: 2014-2018 Gmc Sierra 1500 5.3 gas
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P0420: P0420 Diagnostic Guide
Vehicle-specific published guides for this diagnostic trouble code.
P0420 Diagnostic Guide
P0420 may mean the Bank 1 catalyst is not storing oxygen as expected, so the system may consider catalyst efficiency low.
Article vehicle: 2019-2025 Chevrolet Silverado 1500 5.3 gas
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P0420 Diagnostic Guide
P0420 may mean the PCM sees bank one catalyst efficiency below what it expects during catalyst monitoring.
Article vehicle: 2011-2022 Ford F250 Superduty 6.2 Gas
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P0420 Diagnostic Guide
P0420 may indicate the PCM is seeing catalyst efficiency lower than expected during aftertreatment operation.
Article vehicle: 2011-2025 Ford F250 Superduty 6.7 Power Stroke Diesel
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P0420 Diagnostic Guide
P0420 may mean the PCM is seeing bank 1 catalyst system efficiency below an acceptable level.
Article vehicle: 2015-2025 Ford F150 2.7 EcoBoost
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P0420 Diagnostic Guide
P0420 means the PCM may be seeing catalyst efficiency below the expected level on bank 1.
Article vehicle: 2015-2025 Ford F150 3.5 EcoBoost
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P0420 Diagnostic Guide
P0420 may indicate that Bank 1 catalyst efficiency is lower than the PCM expects.
Article vehicle: 2015-2025 Ford F150 5.0CoyoteGas
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P0420 Diagnostic Guide
P0420 may mean the PCM is seeing bank 1 catalyst efficiency below the expected range, often related to reduced oxygen storage in the catalyst.
Article vehicle: 2020-2025 Ford F250 Superduty 7.3GodzillaGas
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Catalyst System Efficiency Below Threshold Bank 1
P0420 often means the PCM may be seeing Bank 1 catalyst oxygen-storage behavior below the expected range based on oxygen sensor activity.
Article vehicle: 2019-2024 Ram 1500Classic 3.6PentastarGas
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Catalyst System Efficiency Below Threshold Bank 1
P0420 means the PCM may be seeing Bank 1 catalyst efficiency below the expected range.
Article vehicle: 2019-2024 Ram 1500DT 5.7HEMIGas
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Catalyst System Efficiency Below Threshold Bank 1
P0420 means the PCM may be seeing Bank 1 catalyst efficiency below the expected range by comparing upstream and downstream oxygen sensor activity.
Article vehicle: 2019-2025 Ram 2500HD 6.4HEMIGas
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