Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Oxygen Sensor: Testing and Inspection

The Oxygen Sensor if open, should set a Diagnostic Trouble Code (DTC) 13. A constant low voltage in the sensor circuit should set a DTC 44. A constant high voltage in the circuit should set a DTC 45. DTCs 44 and 45 could also be set as a result of fuel system problems. See DTC charts for conditions that can cause a lean or rich system. Testing and Inspection