Possible causes
– Faulty Oxygen Sensor
– Vacuum leak affecting bank 1 only
– Fuel injector problem bank 1
– Check for cylinder misfire on bank 1
– Engine mechanical condition
Tech notes
Though the Oxygen (O2) sensor, the Engine Control Module (ECM) has detected a lean system, which means that there is either not enough fuel or and excessive amount of air in the system. Start by checking for vacuum leaks.
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A Heated Exhaust Oxygen (HO2S) sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
P1131 Lack Of HO2S11 Switch – Sensor Indicates Lean
Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 1
Reference Link:
http://www.freeautomechanic.com/diagnostictroblecodes.html
Possible causes
– Faulty Oxygen Sensor
– Vacuum leak affecting bank 1 only
– Fuel injector problem bank 1
– Check for cylinder misfire on bank 1
– Engine mechanical condition
Tech notes
Though the Oxygen (O2) sensor, the Engine Control Module (ECM) has detected a lean system, which means that there is either not enough fuel or and excessive amount of air in the system. Start by checking for vacuum leaks.
——————————————————-
A Heated Exhaust Oxygen (HO2S) sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
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