Customer?s complaint may include a MIL-on with one or more of the following DTCs (Active, Pending, or Stored) in the PCM: P0133, P0137, P0171, P0300, P2096. The root cause could be due to oil leaking from Bank 1 valve cover seal on to the 1/2 (Bank 1 downstream) O2 sensor. This can adversely affect the 1/2 O2 sensor signal reading and lead to listed DTCs. Before performing normal diagnostic routines for the above codes, check for the condition listed above.
