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)

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Oxygen Sensor: Testing and Inspection

Fig.41 Checking Oxygen Sensor with Voltmeter:




Fig. 69 Oxygen sensor diagnosis chart:




Fig. 69 Oxygen sensor diagnosis chart:







1. Run engine until it reaches normal operating temperature, then connect voltmeter to EFI service connector as shown in Fig 41.
2. Run engine at 2500 RPM for 2 minutes to warm oxygen sensor.
3. Follow diagnostic chart, Fig. 69, and repair system as necessary.