• Simple Item 6
  • 1
  • 2
  • 3

Mazda 3 with fault code P2096 – Post catalyst fuel trim system too lean Bank 1

Mazda 3


  • The only indication is engine light is ON (general no complaints regarding poor drivability)
  • Code P2096


Code P2096 means post catalyst system fuel trim too lean on bank 1. The ECM monitors the air/fuel ratio with an air/fuel sensor and oxygen sensor located on the exhaust. If the ratio is higher than the specified target, the system is too lean.


  • Check fuel pressure
  • Check for intake air leaks
  • Check for exhaust leaks
  • Check air/fuel sensor operation
  • Check bank 1, sensor 1 (pre catalyst) oxygen sensor operation (cycle between 0.1-0.9 volts)
  • Check bank 1, sensor 2 (post catalyst) oxygen sensor operation (approximately 0.5 volts steady)
  • Check fuel trim readings


If no fault is found from the above tests, the Electronic Control Module [ECM] may well need a software update. (Call CoolDrive EFI for further information)