Diagnostic Trouble Code: P0171 System Too Lean Bank 1, P0174 System Too Lean Bank 2 No time to read this article? Listen to it instead! When: DTCs P0171 and/or P0174 are stored when the control unit recognizes that there is too much oxygen in the exhaust based upon readings from the oxygen sensor(s). Why: In
EGR (exhaust gas recirculation) is an emission control and prevents detonation when working properly. At high combustion temperatures, NOx (oxides of nitrogen) is formed.
DTC P0420 is stored when the readings of the pre- and post-cat oxygen sensors indicate that the catalytic converter is not working as efficiently as it should be in accordance with pre-programmed specifications.
TechShop’s The Code Reader Podcast takes common DTCs, breaks down when and why they occur and looks at symptoms and causes to help listeners make an accurate diagnosis.
The Code Reader takes common DTCs, breaks down when and why they occur and looks at symptoms and causes to help you make an accurate diagnosis.