Possible causes
– Faulty HO2S
– HO2S harness is open or shorted
– HO2S circuit poor electrical connection
– Leaking pressure regulator or fuel injector
– Engine mechanical condition
– HO2S harness is open or shorted
– HO2S circuit poor electrical connection
– Leaking pressure regulator or fuel injector
– Engine mechanical condition
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)